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Comment by bkanber | Hacker News Reader

Former automotive engineer chiming in. "Tweels" have been around a long time, but have always failed in terms of "NVH" (noise, vibration, harshness). Michelin is claiming that this generation of tweels are appropriate for passenger cars, which means that they think they've solved the NVH problem.

They seem to be marketing these alongside EVs, I wonder if they're only really intended for lighter, compact-style cars. (Edit: I'm talking about EVs like the BMW i3, which are on average about 1000 lbs lighter than the cars most Americans drive, ie, the CUV/SUV form factor.)

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Complete layman here, every 6 months or so for the past decade I see an article claiming someone got air-less tires working. What are the chances this would be it ?

Air-less tires have been working fine for decades: https://www.nasa.gov/specials/wheels/

You'll also find industrial equipment examples like https://www.sourceproequipment.com.au/crocodile-skid-steer-b...

As the person you're replying to said, though, the problem for passenger cars is NVH. They aren't quiet.

Even with that downside, though, they are still used in consumer-facing applications like some bike sharing programs: https://medium.com/@fredchang/by-now-youve-probably-heard-of...

Where a smoother ride is less significant than unlocking a bike & finding a flat tire.

What the hell, I've been looking for something like this for the past few months. Only ones I could find were Tannus (too soft) and Schwalbe (garbage).

Don't care about weight, noise, ride quality, just need unbreakable tires because riding through neighborhoods where people break glass bottles on the bike paths will make me smash someone's head with one someday.

Panaracer T-Serv Messenger bike tires are what you're looking for. They're lighter than the gatorskins and work incredibly well. I rode one pair until the tread was gone in SF (several years) and never got one flat tire.

https://www.panaracerusa.com/collections/commuter-city/produ...

That's a nice option to have, thanks for sharing. I used Gatorskins (Hardshell and the normal version) until the tread was gone the past couple of years. This year I fitted some Continental Grand Prix 4-Season that are holding pretty well against punctures.

Might give these Panaracers a try when the tread of the GP are gone (or if I start getting punctures but so far they are as impervious as the Gatorskins for me).

Continental Gatorskin brand tires have worked really well in my experience, easily many thousands of miles. They usually age out (2 years or so) before I've had any flat. I have had snakebite flats though which is usually just due to low air pressure or bad tubes. Tubes can just suck. I've combined them with puncture resistant tubes (thicker tubes) and never had a flat, using 700x25 or 700x28 versions.

https://www.continental-tires.com/bicycle/tires/race-tires/g...

I was put onto Gatorskins by a friend around ten years ago, and have never looked back. Great tyre with fantastic grip and lifespan.

They are really solid, last forever and are quite light for a non racing tire. They also have decently low rolling resistance when inflated high.

However, in my experience they are really sketchy in wet conditions. I've wiped out or almost did multiple times on gatorskins. Deflating them in wet conditions works but the rolling resistance is then quite high.

I've found that the Schwalbe Marathons in wider sizes (I think I got 38s?) are much more confidence inspiring and comfortable, and makes up for the fact that I have to change a flat twice a year instead of once a year.

Oh yeah, I've had some extremely solid wipeouts in the wet on mine, but then again I usually just attribute that more to me being a hooligan on the bike more than the tires :P

My Marathons are nice and fast, but slippery on the curves and I'd watch out in the rain

How about just regular Schwalbe Marathons Plus? In my experience those tyres are literally unpuncturable(at the cost of a huge weight penalty).

I rode across the country on a pair (two pairs actually, first set wore out) of marathon pluses. I got 1 flat from a metal staple, which is pretty good for 4200 miles :D

These are great tires, but the rolling resistance can absolutely be felt. They do suffer in grip in wet conditions as well.

The non-Plus Marathons are quite nice, but less puncture-proof.

You can't really win, the stiffer the tire the better it is at protecting the tube but the rolling resistance is higher and the tire flexes less which makes it less grippy.

Weirdly, it's actual black magic - the regular Marathons have the lowest rolling resistance of any touring tyre[0](lower than Schwalbe's own Marathon Racer lol), despite being very good at puncture proofing and not being completely slick. No idea how Schwalbe has actually done it.

[0] https://www.bicyclerollingresistance.com/tour-reviews/schwal...

> Schwalbe (garbage).

I have never read these two words in the same sentence. I've put thousands upon thousands of miles on my Schwalbe Marathons with nary a flat. Granted, nothing is 100%, but I find Schwalbe's a solid urban/touring choice.

same experience here. 'Schwalbe Marathon Plus' are the only pneumatic tires I have used on a wheelchair that last more than a few weeks of hard abuse.

Tannus too soft? I've had mine for a year and a summer, and really couldn't be happier. If anything, I find them a tad on the hard side. This is an ordinary, oldfashioned pushbike with medium-width tyres.

I was regularly getting flats with a new to me road bike.

I switched to Continental Grand Prix 4 Season and haven't had a flat in 2 years in Portland, OR (though my frequency is down with the pandemic).

Schwalbe Marathon Mondial are incredibly durable tyres. Never had a single flat in at least 20,000 km on them.

A lot of heavy equipment drives around with water-filled tires, so it's already there. Definitely not what you meant though.

Hmm, why water filled? I can't think of any advantages, but can think of downsides such as a massive increase in unsprung weight.

Ballast for increased traction and tipping capacity with the positive side effect of lower COG.

Ah! That's a good idea.

The only springs on most tractors - ancient or modern - are between the seat and the frame to which it is affixed. IOW the vast majority of the tractor's total weight is unsprung.

Its easier to let the water out of a tractor tire than to take a 500lb wheel plate off...when changing a tire.

...added weight is for better traction. Almost all 2WD tractors will have their back tires filled with a water/radiator fluid mixture (ice doesn't work well if you want to keep the tire on the rim).

Water's basically incompressible, if some Michael Crichton book I read like 25 years ago is to be believed.

My guess would be one or more of: the above; greater heat capacity; or, something to do with surface area vs. volume meaning that at a large enough size water in a tire is far lower-pressure and easier to contain than air at a high enough pressure to keep it inflated, and/or, relatedly, something to do with heat dissipation from compressing gasses being really hard to deal with once you hit a certain surface-to-volume ratio.

[EDIT] LOL, guess all these were wrong and it's just for the extra weight.

The book was Sphere. It rocked. I too remember this fact just from that.

which was made into a movie

https://en.m.wikipedia.org/wiki/Sphere_(1998_film)

that is confusingly similar to The Abyss,

https://en.m.wikipedia.org/wiki/The_Abyss

I always get the two confused.

https://tractoraddict.com/tractor-tires-filled-with-water/

Beet juice is interesting! lol

It's a lot better than the calcium chloride that they used to use, when a telehandler blew out a tire and drained hundreds of pounds of saltwater into my parents' lawn a few years ago it did a lot of damage.

Beet juice is soooooooo much better for the environment than the salts it is replacing. Unfortunately it is slightly more expensive so we get to continue poisoning our waterways with salts.

Sounds like it’s used as ballast: https://tractoraddict.com/tractor-tires-filled-with-water/

The only time they move fast enough to worry about unspung weight is when they are on a trailer.

That isn't strictly true, but in general such equipment spends most of it time moving very slowly it it moves at all. Transports speeds do become a problem, but that is only done for a short time (or you have it on a trailer so you can go faster) so nobody worries about the issue.

Nothing is sprung on a wheel loader or a scaper.

A disadvantage is that only the rubber absorbs impacts, since the fluid is incompressible for all intents and purposes.

The tyre is only partially filled (for example 40%) with water - so the tyre is not “incompressible”. https://salesmanual.deere.com/sales/salesmanual/en_NA/tracto...

I see. Furthermore, there is an admonishment:

IMPORTANT: Never fill any tire to more than 90% full. More solution could damage tire.

... but for 'intensive purposes' on the other hand the story is less clear

Sometimes foam is used rather than water.

Also trains drive around with solid metal tires.

Trains have the benefit of exceptionally smooth "roads"

At some point they will be viable... whether this is that point or not is yet to be seen.

> At some point they will be viable

Why do you assume this?

Because at some point we used wood for wheels?

How does wood --> inflated rubber imply inflated rubber--> airless rubber? I don't see any logic in that.

You can still use wood if you want.

Many of the reasons you don't are the same reasons airless tires have not escaped niches.

Hmm, not the worst idea. But who makes wood tires for bikes nowadays? And oh God, the splinters :D

We still do use wood for wheels... So...

Because this is primarily a materials science problem, and we are still novices at materials science.

There does not have to exist a solid material with the properties of a gas.

What? I don't understand what you mean by that.

There's no reason to assume this is a solvable problem, just because it's a new field. I remember when cold fusion was considered inevitable.

You don't actually have any reason to assume it will happen other than blind optimism.

... you don't actually have any reason to assume it won't happen other than blind pessimism. So let's just agree to disagree.

I love to disagree because I'm a betting man. Want to wager some money on a bet? Pick a timeline (5 years, 10 years, 20 years, 50 years) and maybe we can make this fun!

lol. No bet. Not because I doubt my position (I see an aerogel-inspired material working out). Rather because the 50 year timeline that I would feel safe betting on is basically my end-of-life. I'm not really interested in paying out a longbets.org payment on my deathbed.

As he said, more or less. Sorry for being cryptic.

"There's no reason to assume this is a solvable problem"

I use nitro oxygen in my tyres. Pressure problems are gone.

The Earth's atmosphere is about 80% nitrogen and a little less than 20% oxygen, with some carbon dioxide, argon, variable amounts of water vapor, and some pollution.

What's "nitro oxygen", then?

My guess is parent comment misspoke and meant pure nitrogen -- which does indeed help with tire pressure. The ideal gas law still applies, so there will be seasonal changes in pressure, but there will be much less exfiltration (via 'permeation', specifically) of gas through the material (N2 has a larger 'kinetic diameter' than O2; O2 will permeate 3-4x faster through rubber than N2).

So if regular air is 80% nitrogen already, won't the tires move towards 100% nitrogen with each top off since the tires will be retaining the nitrogen more than the oxygen? Sounds like a marketing trick unless they're filling newly mounted tires with 100% nitrogen.

That's a pretty clever thought in general, but yours is only a first approximation.

First, permeation decreases with pressure, at different rates for the two gases. If you consider only this fact you will find that the partial pressures of O2 and N2 asymptotically approach homeostasis, rather than simply all the O2 leaving and all the N2 remaining.

Second, permeability changes with temperature, so the ratio of O2 and N2 exfiltration rate changes seasonally, as each gas has a different permeability-vs-temperature curve. Third, the ideal gas law causes pressure changes seasonally which will also decrease exfiltration in winter, and once again, each gas will have its own permeability-vs-pressure curve, so these become very confounding factors.

All in all, the reality of the situation is that filling up your tires with atmospheric air will probably settle on partial pressure ratios of, say, 85/15 rather than 100/0. The deflation that you get comes from only about 5% of the O2 leaving the tire; and of course you get another big deflation when the weather first turns cold.

I don't know the exact numbers because I've frankly never thought to look into this before. So like I said, it was a clever thought! But it needed to be taken a few steps further.

Thanks! I love getting answers like this from the community.

Maybe just nitrogen? Costco inflates tyres with nitrogen. The pair of tyres on my vehicle inflated with nitrogen don’t seem to lose pressure, the other two need topping up occasionally.

That's the point. He's being sarcastic and calling "atmospheric air" "nitro oxygen"

I imagine it's a joke on people that use nitrogen.

https://www.tireamerica.com/resource/nitrogen-vs-oxygen-for-...

That at least helps with some of the logic. However, doesn't directly answer what "nitro oxygen" is. Guessing some sort of slang. It's definitely not a scientific phrase. Nitrogen oxide or something maybe too much for grease monkies so they call it nitro oxygen??? just guessing.

Maybe the noise they generate is good for EVs which are dangerously quiet for pedestrians?

Valid point, although pedestrian safety is mostly discussed in the low-to-mid-speed regime (<= 45 MPH), while tire noise (at least according to my own observation) dominates in the high speed regime (>= 65 MPH). There might be some overlap though.

Also worth pointing out: NVH is not just Noise --- it includes Vibration and Harshness that are only felt by the people inside the vehicle.

And effective at rattling off any untorqued/loose nuts/bolts.

You can ear an EV very well, the rolling noise and the wind noise is difficult to miss. Of course if the EV is driven very slowly it's not noisy unless it has a fake sound like many does, but it's not very dangerous either.

Ironically NVH is even more important in EVs since the engine noise no longer drowns out unpleasant sounds like fan motors, hums, squeaks/rattles

Every EV sold today must make noise at low speeds.[1]

1. https://en.wikipedia.org/wiki/Electric_vehicle_warning_sound...

Some EVs have mandatory sound emitters to not be fully silent (and thus dangerous). I thought it was weird harmonics from the synRM engine but it's synthetic and enforced by regulations.

Hybrids as well. The Toyota Prius has had this at low velocities since before EV cars were mass produced (I believe Toyota uses a speaker that makes a sort of sci fi sound). It is a legal requirement to generate a minimum amount of noise to sell a car in some countries.

I thought it was a plastic valence rubbing on something.

nah it's on purpose https://www.youtube.com/watch?v=mNkGD_Sryxg

Noise is not good, ever.

Don't get me wrong - I'd expect Michelin to have done some testing to see NVH is within tolerance levels right?

Airless is really close to working for bikes. If I were commuting on a bike now I'd be comfortable going for it. The downsides - painfully hard installation, uphill resistance, ...etc. - will be worth it.

I also want to add, since this is more of a deep auto-industry thing, that NVH testing is almost like longitudinal health studies. NVH engineers actually have charts of which specific frequencies our internal organs resonate at. For a layperson it's easy to imagine that NVH testing is just a matter of setting up a dB meter and some accelerometers to make sure things aren't bouncing around too much, but it's actually much more nuanced than that, and the engineers have to consider the long-term effects of driving in the vehicle.

One easy way to picture this is: recall your last long road trip, or airplane flight, anything more than 3 hours or so. You get so tired after those, especially considering that you've only just sat still for a few hours. But in actuality your body is making hundreds of tiny corrections to posture each minute, in response to the vibrations of the vehicle, and that literally exhausts your muscles and nervous system. Now imagine that you make that car "5% more harsh" and redo the road trip; you will feel the compound effects of that additional harshness. Auto manufacturers take NVH very seriously, because it turns out to be a pretty big deal.

My point is that even if NVH comes back OK in the lab, they still will need a good deal of real world data with test subjects representative of the 'average driver' before they can make a determination.

Edit to add: I know of at least one case where the entire drivetrain of a vehicle was redesigned due to NVH.

And this stuff is exactly why it's a million times less fatiguing to drive a vehicle from 2020 over one from 1990, even if you control for almost every other variable by picking one that has changed minimally (i.e. a few panel vans and many medium duty trucks)

That's a wild over exaggeration.

That certainly puts an interesting spin on the one time I had to ride the back of a bus from west coast to east coast. It was three days and I was physically and mentally exhausted at the end despite sleeping for a fair chunk of it.

Edit to add: Thanks for your input on this, it's insightful and interesting!

A friend recommended I wear earplugs on plane flights, for a similar reason. He said that the constant noise stresses our bodies/minds, and lowering it makes the time more pleasant. It may entirely be placebo effect, but I find it very helpful.

Thanks for this. Is there a way to look up NVH values for current tires? I'm assuming some have better NVH values than others and they could have an effect on making the drive feel nicer.

This was very cool to read; thanks for such an informative comment.

I imagine this will sound naive, but I wonder why this sort of vibration can't be addressed with shock absorbers in the seats?

> I wonder why this sort of vibration can't be addressed with shock absorbers in the seats?

Not at all naive, because it is addressed with shock absorbers in the seats; that is one of the very many tools NVH engineers use. :) But they're not 'shock absorbers' in the way you're thinking; the actual foams used in the car seats are specifically designed and selected to dampen certain frequencies. But, kind of like a speaker or headphones or even ear plugs, the dampening happens over a spectrum, and in general our organs resonate at lower frequencies, which are harder for foamlike materials to dampen.

NVH engineers view the entire road-vehicle-driver system as a huge, complex, spring-mass-damper system, and do a whole ton of partial differential equations to solve for the outputs.

Edit to add: so why not use traditional 'shock absorbers', the spring-damper kind that you're used to seeing? For passenger vehicles the answer is weight and complexity. But many trucks and tractors and so on do in fact have these.

Fascinating, thanks for the response.

Really? There are small cans of spray which you can have easily with you. Got a flat? Look where, pull it out. Spray the foam in. Turn the wheel for a minute, look for overseen leaks, maybe, and pull stuff out of them. Turn wheel a few more times. Pump. Or use car-adapter for pump at gas station. Those stuff costs between 2 and 4€ for a can of sprayfoam, and maybe 50ct for a small adapter(sugar cube like, but cylindrical). Given the stuff Schwalbe and Continental are offering for normal bicycles, I don't get all the rage. Because a flat fixed like described above lasts about half a year, then the profile is too slick, and I change tire and tube.

Works for me. Feels comfortable and fast. Is economic.

YMMV.

You make it sound simple. It's not when I'm commuting. Even to use the sprayfoam sealers - I need to first identify the puncture and that's not always obvious. I've usually just changed the entire tube.

It's my experience. In case of unidentified punctures the foam leaks out (of them), and then you can remove the splinter, or whatever by hand, maybe with a paper tissue, or tweezers from your swiss officers knife, some multitool. Dunno. I don't have that many flats. About 5 or 6 since 2005? Each one maybe a 10 to 15 minute break.

edit: Thinking about it, one could even omit the spray can because in cities there's almost always a gas station near, which is stocking that stuff. So only the small adapter would be necessary, if your valves aren't like the ones for cars anyways. I didn't do that so far because I'm often bicycling out of the city, instead of into it.

The last flat I had involved a 3" split in the tube - ain't no slime/foam/spray can that's gonna fix that.

I just used aramid fiber lining on the inside of my Vee Rubber tires (best stuff, fuck Conti and Schwalbe), haven't had a flat yet. Better than "puncture proof" shit from Conti.

But it's probably just a matter of time before an exotically shaped piece of glass gets through :D

Bridgestone said bike tweels were close 4 years ago, and then again 2 years ago... I won't hold my breath! :)

Tannus is the leader right now. I have tried it and I'm fairly comfortable. Again, the number of flats you get in some of the cities in the Bay Area is insane. That makes it worth it.

Michelin is by far the market leader in tires, especially compared to Bridgestone.

EVs are quite heavy for their footprint due to the weight of the batteries.

There are exceptions though like the upcoming Aptera which only weighs around 800 kg even with a large range.

I'll believe it when it happens. Aptera has gone out of business more times than they have released a production car.

I remember being excited about the Aptera twelve years ago. I’ll maybe get excited again once they actually start shipping a vehicle. They’ve already gone out of business once.

Unfortunately, they are also making a lot of claims that they haven't demonstrated in a working vehicle yet. Getting to production is going to be hard.

This will change with improved batteries, charging infrastructure, and shrinking EV tech. By the time this could hit the market, hopefully the weight difference would be less stark.

EVs are usually much heavier than gas cars.

I don't think that's true anymore. For example, the Tesla Model 3 weighs anywhere from 3,552-4,072lbs depending on the trim level.[1] (The heaviest is the Model 3 Performance which has the biggest battery, motors, and wheels.) The BMW 3 series is 3,582-4,138lbs depending on the exact model and trim.[2]

Gas cars don't have big heavy batteries but they do have big heavy engine blocks and more complicated (heavier) drivetrains.

1. https://en.wikipedia.org/wiki/Tesla_Model_3

2. https://www.caranddriver.com/bmw/3-series/specs

BMW is a particularly heavy sedan. The Honda Civic is 2877 to 3126. Even the Golf R which has a rear diff, DCT, and a 2.0 turbo is only 3100 pounds.

I picked a gas car of comparable size. The Civic and Golf are much smaller than the Model 3.

The Civic is 2 inches shorter and 2 inches narrower than the Model 3, but it actually has a larger interior volume by one cubic foot.

Size up to the Accord which is 8 inches longer and a half inch wider than a Model 3 (and 9ft^3 more interior space), and it still only weighs 3131-3362 lbs.

Where are you getting those figures? When I look up the stats for the 2021 Accord I see weights ranging from 3,150-3,446lbs.[1]

Really though, the Civic and Accord aren't competing with the Model 3. They're front wheel drive. They have less power and torque. They use struts for the front suspension. All of these measures save significant weight (and cost). That's why I picked the BMW 3 series. It's similar size, performance, and cost. If we look at other competitors to the Model 3 we get similar weights:

- Volvo S60: 3,724-4,468lbs. (The low number is front wheel drive. The high number is a plug-in hybrid.)

- Audi A4: 3,682-3,726lbs.

- Mercedes C-Class: 3,472-3,605lbs.

- Cadillac CT4: 3,422-3,616lbs.

- Volkswagen Passat: 3,014–3,794lbs. (The lighter versions are front wheel drive only. The heavier versions are hybrids.)

In general, fancier cars are heavier. Also safer cars tend to be heavier. Yes batteries are heavy, but so are engines, drivetrains, starter motors, turbochargers, exhaust systems, fuel tanks, and so on. Early electric cars were significantly heavier because they were based on combustion platforms. When EVs are designed from the ground up, the weight penalty is less than 10%. Vehicle models in the same market segment vary more than that, and some combustion vehicles are already heavier than their electric competitors. This will likely get better with time as battery technology improves.

The statement "EVs are heavier" is approximately as true as "AWD vehicles are heavier". All else equal it's more likely than not, but the difference is rarely enough to matter for any practical purpose.

1. https://www.caranddriver.com/honda/accord/specs/2021/honda_a...

And the GMC Yukon is 5500-5800 lbs, which is what I expect the original comment to be making a comparison with.

GMC Sierra, maybe, but as far as SUVs go, the Yukon/Escalade/Suburban/Tahoe are not a very popular size of SUV in the US. They're too dang expensive for most people.

The RAV4, CR-V, and Rogue are the top 3 best selling SUVs in the US so far this year. They're about half the price of a Yukon. The rest of the top 25 are almost all sedans, similarly sized midsize SUVs and pickups.

The 3 has at least 5 cubic feet more in cargo space than the Civic. In practice there is a pretty big difference between those two cars.

The Civic and 3 both have 15 ft^3 of cargo space according to the EPA.

Regardless, the Accord dwarfs it and supports the above point that the Model 3 is a heavy car, and the BMW 3 series is heavy because it was built to have a premium feel as a design priority, not because it is ICE.

That's odd, I had no idea the EPA even presented a spec like that. It must be a difference in how they estimate it.

The BMW comparison is interesting as the performance numbers are similar. The 3 series heft vs a civic is largely due to the engine and drivetrain choices. Its much easier to optimize weight on a low powered FWD car.

And an e-Golf weighs 3455lbs. Which - sure, is 10% heavier than a Golf R. But then so, apparently, is a heavy Civic compared to a light one.

For the same form factor, yes that's true.

Last time I tried estimating; EV's are about 25% heavier. Improvements in battery energy density will probably erase that inside 5-10 years.

Sorry for the conversation pivot, but this attitude sucks and is terrible for climate change and was decided wholesale by suppliers. While SUVs are leading sales in the US, it was the decision by car manufacturers to discontinue sales of anything other than SUVs in the US. That you say, "well these wheels which would reduce waste aren't useful for Americans," they are partly not useful because the car industry here pushed through advertising pressure (and yes, due to demand in part) for that outcome, it's a coupled two way street. So, that same industry bears some of the blame.

Nah...americans like big cars and manufacturers followed the sales! Even worse, europeans started to like big cars too...I just don't get why people like to drive big SUVs in the city.

> europeans started to like big cars too

I saw a documentary on this once where they interviewed some psych guy who was advising the car industry. He said that it took him some time to convince them to make everything ridiculously big. Not just the car, but the lights etc. It was based on his theory that when we first see something we evaluate it using the bit of our brain that has been there since we were lizards. And that bit is impressed by size. His theory was that it overrides everything. Most people will pick the bigger thing. He was right.

> His theory was that it overrides everything. Most people will pick the bigger thing. He was right.

Wouldn't that mean that most people---regardless of culture, education, etc.---would pick SUV over sedans? Is that true?

Granted there are plenty of SUVs in the US, but as far as I can see on the road and parking lots, sedans are still quite popular. I even see a lot of Minis and Beetles, which are even smaller than a regular sedan.

Yeah the role of marketing in influencing public opinion should not be discounted.

That was public opinion influencing marketing.

I mean the public relations industry is all about a few people having an idea and figuring out how to convince lots of people. Just look at how cigarette sales to women were pushed with intentional ad campaigns to change public opinion. They of course need to craft their message in a way that appeals to their audience (for example calling cigarettes "torches of freedom" to appeal to progressive women in the 1920's) but the message "buy cigarettes" is decided by the marketer.

https://yourstory.com/2014/08/torches-of-freedom/

Nah. SUVs above a certain weight pay less taxes [0], that's why automakers aggressively marketed them for decades and finally managed to convince Americans that SUVs are cool.

[0]: https://www.irs.gov/publications/p946

The vast majority of people don't commercially depreciate their vehicles, so while this does apply to some, it's a relatively small group.

In my huge group of friends, I know one person who does this with his truck, and he readily admits that it involves lying to the IRS and it fraud. Everyone else with a big SUV just prefers them to minivans.

There is also a gas guzzler tax that only applies to cars. If it was applied evenly, most trucks and SUVs would be paying a tax penalty for poor mileage. So there is a kind of indirect government subsidy to bigger vehicles. It is a dumb policy, but it's not why people like SUVs.

I'm not trying to defend myself or anything since I don't even have a car, but when I did, it was always an SUV. It wasn't so much a matter of preference as necessity. I'm not exactly huge, only 6'2", but if I try to drive my wife's GTI, I'm hunched over and hitting my head on the ceiling. Only way to do it is leaning severely back with the seat reclined. Trying to be a backseat passenger in an average sedan is completely impossible. Even though it's at least possible to drive a car like that, if not comfortably, it definitely isn't safe, since visibility is shot to shit with the tiny mirrors and your head and elbows running into something every time you try to turn to cover your blind spots.

Contrast that with an SUV. No need to lean or hunch. You can see everything without trouble. You can move without trouble. It's actually possible to use the backseat.

What? I'm about the same height and drive a sedan just fine, and it's comfortable and safe. I don't know how small your wife's car is, but I've never been in one so small that I'm bumping my head in the ceiling, that would be weird.

GP is probably proportioned like Michael Phelps: short legs, long torso.

I'm of a similar height, but oppositely proportioned, and the driver's seat in most cars doesn't go back far enough that my lower thighs rest on the seat, which makes for a lot of butt discomfort on long trips.

If the seat does go back far enough for my legs to be comfortable, it's almost unavoidable that the steering wheel is uncomfortably far away, and I put the seat pretty close to bolt upright to put my shoulders closer and reduce the impression that I'm hanging on to the wheel for dear life as it's trying to pull away from me.

Bicycles are similarly problematic: I want a shorter top tube than is common for my nominal frame size, so I ride a 59cm road bike frame with a short stem and a lot of seatpost showing. You'd be more likely to find somebody with my inseam (34" [0]) on a 61cm or 63cm frame.

[0] Sorry for the mixed units. I'm giving them in the trade sizes. Road bikes are sized in metric, and pants are sized in inches, at least in the US.

I'm an inch or so taller than you and have driven a GTI, along with other small cars, very comfortably for more than 10 years.

Clearly this is a situation where, quite literally, YMMV.

Have a look at the current model Honda Accord. It's a midsize car, but the engineers have somehow managed to create an extremely roomy cabin. 6'4" people can comfortably sit in the rear seats.

The interior space of an MPV is typically bigger than an SUV.

Considering the sales numbers of MPVs, it would seem that the argument you make is not what is pushing the disproportionate commercial success of SUVs.

This problem with sedans sounds so surreal to me. I'm 6'4" and my car is 2005 Toyota Yaris hatchback. And that cars feels comfortable without any special adjustments.

This is why regulation is needed. States do not allow any kind of car on the streets. But often car manufacturers say it will threaten economy and labor.

"Like" is a strong word.

On the one side you've got the tragedy of the commons that is big vehicles are less safe for other people to be around unless they two are in a big vehicle.

On the other side, Tesla, Toyota, Honda, and Nissan still all have relatively strong sales of sedans in the US. The US market decided that sedans were best from "imports" decades ago and GM/Ford just gave up trying to compete. Then there's of course Tesla telling GM/Ford exactly where the hockey puck was going if they wanted to compete with "imports".

There’s some truth to that – remember the surveys where parents said that they could imagine driving an SUV but not a minivan if they divorced & were dating again? – but they were also subsidized. If the price of gas wasn’t artificially low, or they had to meet the same safety and pollution standards as everything else, they’d be less popular. We did at least close the Hummer tax write-off, but we should be doing more on the safety front since SUV drivers reversed a decades-long run of fatality reductions.

It doesn't work like that anymore.

99% of the "SUVs" you see today are CUVs, which in turn are barely more than a lifted sedan.

So the difference is gas milage is miniscule, to the point gas prices will no longer affect the sales of the most successful SUVs

I used to drive a sedan and it felt like I was dropping down on entry and climbing out on exit. Along came kids and I've been driving a mini-van instead ever since.

One thing I really like about the van (Honda Odyssey) is that you step slightly up to enter and step down to exit. Very comfortable. And this is on a car that's so low to the ground (good for little kids and old dogs) that it's like a snow plow if there's more than a few inches of snow.

I want something lifted more than a sedan so I step up to enter and also has more ground clearance for snow, potholes, rough roads, etc. But that doesn't mean 44" tires with a lift kit.

Not sure where you live but the popular models around here are the 15mpg types and the drivers are … not driving efficiently so they're unlikely to be reaching that. You will see a few of the higher-MPG models like a RAV4 but at the end of the day it's a physics problem: all of that extra weight, non-aerodynamic design, and over-powered engine add up.

Now, it's true that someone dropping all of the extra cash for one is less price sensitive but we're still talking a pretty big difference going from mileage in the teens to the 40+mpg a decent car gets. High gas prices would get at least some people to reconsider, especially since you have to pay a fair premium as well.

Ignoring for a second that of the top 3 best selling SUVs in the US, the top two share a platform with sedans that weigh nearly the same amount, have the same engine options, and have very similar Cds ...

None of those physics issues are specific to SUVs. Even full size SUVs end up on shared platforms with full size sedans, with "reasonably close" weights (essentially take a well optioned sedan and it weighs around what the base SUV version does)

With the focus on all of these automakers on modular platforms, we've reached the point where even the largest SUVs could meet the exact same standards their sedan counterparts do and not really change at all.

While SUVs are leading sales in the US, it was the decision by car manufacturers to discontinue sales of anything other than SUVs in the US

?? Cars are available for sale in the US.

https://www.statista.com/statistics/199981/us-car-and-truck-...

Do you think something like this would be made available for motorcycle tires? Motorcycles are significantly more vulnerable to tire-caused crashes because a motorcycle whose one tire violently decompresses on a highway or autobahn is very likely to have a crash since it can no longer balance, while a car that loses a tire still has 3 other tires and will still have plenty of traction and balance left to pull over. Something like this that makes violent decompression impossible would be a fairly big improvement to motorcycle safety.

I wonder this myself. I'm not sure the technology is ready for street bike speeds, but some of the speeds you do on a dirtbike with tight turns and technical terrains.. maybe.

https://www.rockymountainatvmc.com/tires-and-wheels/michelin...

An "equivalent psi" of 13, which is basically what I run my dirtbike at anyway in the New Hampshire forest trails. Although this is slightly different since it replaces the tube not the whole tire.

I remember Michelin talking about these before but seem to recall that the biggest impediment was cannibalization concerns from existing departments.

Does the focus on NVH imply that the increase of rolling friction over time is negligible compared to the tread lifetime ? Or is that partly of the reason to target lighter vehicles.

The above assumes the spokes(?) become stretched over time it would increase displacement of the center of rotation from the center of mass which if recall is what creates rolling friction.

For two tires with equal interior volume, the rolling resistance of a tweel will be much much greater than the rolling resistance of a normal tire.

That said, tweels are typically designed to be much thinner and have much less interior volume than air-filled, in order to close the gap in rolling resistance. So you'd really need to compare a specific model tire against another specific model tweel in tests to know. But my intuition tells me that the rolling resistance will still be worse almost no-matter-what with today's tech.

So that's partly the reason they target lighter vehicles, and that's partly the reason they seem to be marketing around EVs specifically. That extra rolling resistance may be worth a few $s in gas each month vs only a few cents in electricity for the same driving conditions.

The marketing focuses heavily on reduction in disposed tires as the environmental benefit. If the tire were equal in terms of rolling resistance we'd see them at least mentioning it in the graphics.

I understood this was a tough problem to solve when I swapped my hard-to-inflate scooter tires with some cheap tweels. NVH, even at 15MPH, is real.

For anyone wanting to do this to their electric scooters, dont... until Michelin makes a scooter form-factor wheel I suppose.

I'm interested in how they maintain balance if mud or ice gets in some of the gaps. Are they just shaped so that the dynamics while rolling flex the ribs & tread in such a way as to expel any such contaminants?

Compact EVs aren't "lighter" though, are they? I wonder if it is the inverse of that - heavier compact-style cars with relatively large amounts of sprung weight.

The issue with tweels is generally the unsprung mass, not the sprung mass. In general they will want to install tweels on vehicles with lower unsprung mass, which means smaller form factor (again, in general).

And I should have been a little clearer in my parent post: I'm mentally comparing something like the BMW i3 to something like the BMW X3; the i3 is about 1000 pounds lighter.

Also don't you need to change the traditional car suspension system (McPherson struts, wishbones, shock absorbers etc ... ) to even use these tyres ???.

This does still look to be a marketing excercise for now - I see no product availability to market in 6-12 months still.

For utility vehicles on sale now, it seems:

https://tweel.michelinman.com/michelin-tweel-family-of-produ...

That product has been out for 5+ years I think (at least). Plenty of airless in low speed / farm type applications.

The real thing here would be high speed (65+) with good ride / noise.

Maybe launch on local fleet delivery vehicles first (ie, neighborhood driving etc) if there were some lighter options there? Service pickup trucks (light?).

EVs don't have space to store a donut so an airless system that can't deflate would be useful.

That's malarkey. EVs have more than enough space for a donut. If manufacturers choose to not ship one, that's because they can same $$ and weight by not doing so - it's not due to space.

I drive a compact PHEV and there is literally no place to even put a spare, but that may be more because it's a PHEV and so it has to make room for both batteries and engine. I know most compact EVs don't come with spares and many don't even have a well to store one in.

Is there a reason this technology is not used on bikes which weigh a lot less?

Because for a bike it's much simpler - make the tire solid, or a reasonably solid foam, and you're done.

These have been available for years - look at Tannus for a good example.

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