Michelin Airless
michelin.com
michelin.com
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.)
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.
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.
https://www.panaracerusa.com/collections/commuter-city/produ...
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).
https://www.continental-tires.com/bicycle/tires/race-tires/g...
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.
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.
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.
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).
...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).
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.
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.
Beet juice is interesting! lol
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.
IMPORTANT: Never fill any tire to more than 90% full. More solution could damage tire.
Why do you assume this?
Many of the reasons you don't are the same reasons airless tires have not escaped niches.
What's "nitro oxygen", then?
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.
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.
Also worth pointing out: NVH is not just Noise --- it includes Vibration and Harshness that are only felt by the people inside the vehicle.
1. https://en.wikipedia.org/wiki/Electric_vehicle_warning_sound...
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.
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.
Edit to add: Thanks for your input on this, it's insightful and interesting!
I imagine this will sound naive, but 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.
Works for me. Feels comfortable and fast. Is economic.
YMMV.
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.
But it's probably just a matter of time before an exotically shaped piece of glass gets through :D
Gas cars don't have big heavy batteries but they do have big heavy engine blocks and more complicated (heavier) drivetrains.
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.
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...
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.
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.
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.
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.
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.
Clearly this is a situation where, quite literally, YMMV.
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.
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".
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
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.
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.
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.
?? Cars are available for sale in the US.
https://www.statista.com/statistics/199981/us-car-and-truck-...
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.
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.
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.
For anyone wanting to do this to their electric scooters, dont... until Michelin makes a scooter form-factor wheel I suppose.
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.
https://tweel.michelinman.com/michelin-tweel-family-of-produ...
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?).
These have been available for years - look at Tannus for a good example.
Regarding catastrophic collision with sharp edge, I think these tires will be susceptible as well. If it's enough of a bump to "bottom out", it's going to dent the rim.
Also, your comment about potholes reminded me of a time that I was driving with a friend and we hit a pothole and got a flat. My friend was driving and looked a the flat front tire and said "I'm glad I have a spare". I look at the flat back tire and said "Unless you have two, we're still going to need assistance."
I did this one time. Ran over a pothole and bottomed out. As I'm replacing my front tire I look to my rear tire and see that it's also flat. That wasn't even the cherry on top. At that point I had my front wheel off and tried putting on the spare anyways.
I had a Kia Stinger GT and the GT version has Brembo brakes which have a much larger caliper than the regular version. Well QA at Kia never thought to check if their spare tire actually fits with the larger caliper. Spoiler alert: it doesn't.
The manual stated something about putting the spare on a rear, then, taking the good rear and putting it in the front.
The rotors on the rear were smaller and could accommodate the spare. Obviously a moot point if one has two blown tires.
That was a rough day.
Not sure. Makes me think that it would be a good idea to make the inner rim diameter smaller, and have another layer of spokes/spings with a higher compression force.
Filling tires at too high pressure can lead to blowouts.
Filling tires under pressure leads to degraded performance handling issues potentially causing accidents in some cases.
A more consistent normalized baseline performing tire, even if louder, would be welcome. This would end the seasonal low pressure tires in winter due to the cold and higher pressure during summer due to the heat.
One time we got new tires and went on vacation and parked our car in an outside parking garage in a hot summer for a week, we came back and the side facing the sun the tires had exceeded PSI max and started to buckle. I am sure we have all seen those videos of people standing over tires and overfilling them leading to essentially a pressure bomb. Managing air pressure in tires can be problematic, airless tires are a welcome innovation.
Background noise can lead to fatigue, which can lead to crashes. I have no idea of the overall impact (pardon the pun) of this, compared to increased safety of (louder) tyre performance, but probably worth considering.
> Managing air pressure in tires can be problematic, airless tires are a welcome innovation.
True, but modern cars have inbuilt pressure sensors, and these can be retro-fitted relatively cheaply.
I lose 1-2 tires per year due to sidewall damage from potholes. Lucky for me, the Discount Tire road hazard warranty covers that. Costs me $16/tire each time this happens.
It's so bad that I had to replace the factory wheels with aftermarket ones that wouldn't get bent from the impact.
Of course, I didn't consider changing the wheel size when I did that. I should have gone with 15" wheels and a higher ratio tire to get the same effective outside radius with more tire between the wheel and the road.
Oh well, replacing this car soon anyways as now I am in need of ground clearance and AWD due to having moved to where roads do not always exist year round.
Not clear whether these new airless tyres will help or worsen that. More resistance = more wear, I would assume. Anyone?
https://www.imperial.ac.uk/news/195595/worlds-first-device-c...
We received and chain forwarded a "leaked" video of Michelin testing a similar design.
We ICT folks thought we were doomed as it seemed miles ahead of our own R&D.
16 years later and we are yet to see these tyres on the streets.
This time, I'll believe it when I see it ;)
But..... one of the most important aspects about trailer tires is cost and these may not quite be there yet. Michilin and other tire manufacturers don't really compete much in that space and leave it for the low end import brands to fight over.
Rental trailers and towed equipment (like towed light plants and air compressors) seems like the only obvious niche where both the cost and downsides are justifiable.
For a consumer product like this I think it's probably more important to compare the common case than the optimal case, because I know my tires often aren't in an optimal state, and as much as we could save as a nation by making sure tires were inflated correctly, we just don't, and I don't expect that to change meaningfully.
So I guess the question is how does 0.6% fuel economy loss on average for current tires compare to the loss in efficiency for using a Tweel, but according to some data from Michelin here[2], it looks like they're actually projecting them to be more efficient than current tires? I didn't read through the whole analysis, so I'm not sure, but that's what Table 7 looks like to me at a cursory glance and reading a few paragraphs in that section.
1: https://www.fueleconomy.gov/feg/maintain.jsp
2: https://manufacturing.gatech.edu/sites/default/files/uploads...
The money shot is here. Note that '5.5 kg/ton' refers to the rolling resistance of the tire.
> At this point the 5.5 kg/ton value is still only a design target, and this study serves mainly to confirm the environmental value of achieving that target.
Essentially, this conclusion is tautological. "If there were a tweel that had better rolling resistance than the best pneumatic tire on the market, then it will have a better fuel economy and environmental impact." Obviously!
I seriously doubt Michelin's tweel is anywhere close to that 5.5 kg/T mark. It's more likely something like 12 kg/T.
The purpose of this particular paper is not to show that tweels are better environmentally, it is to show an analytical framework for calculating the full-lifecycle environmental impact of tweels vs tires. Sort of like a "here are the equations, plug in real numbers later" kind of thing.
The TREAD law does not specify when TPMS must alert, other than the tire being 'significantly underinflated'.
[1]: https://www.nhtsa.gov/sites/nhtsa.gov/files/fmvss/TPMSfinalr...
[1]: https://www.nhtsa.gov/sites/nhtsa.gov/files/fmvss/TPMSfinalr... (page 10)
Airless tires give up this advantage, and only the tire structure between the wheel and contact patch are available to do the same work.
The result is always a heavier tire that is a harsher ride. All the materials science in the world can't and won't find a solution to this. You can safely ignore any airless system for all but the most specialized applications.
"""
I am an engineer working in the tire industry (throwaway is needed here). The Michelin "Tweel" IP was actually acquired when Michelin bought BF Goodrich 31 years ago. Goodrich developed the concept as a replacement for compact spare tires, doing the initial R&D in the 1980s. Every 3--5 years Michelin has a press release like this, and the technology is always 3--5 years away from release. Currently the US DOT and it's equivalents abroad are still in the rulemaking phase regarding airfree technologies, so there's that, too.
"""
Also, I see the biggest concern as degradation of tyres contributing to rubber-dust pollution: "according to the UK government, and they are the second largest source of microplastic pollutant in oceans after single-use plastic"
Seems like it would be better to find an eco-friendly alternative to tyre rubber instead. If this design allows that (e.g. by allowing tyre materials that aren't as stretchy as an inflatable would need to be) I'm all for it, but that's a more complicated definition of "good for environment", dependant on other tech being developed.
However, there is still the problem of getting rid of "a flexible load-bearing structure made from glass fiber reinforced plastic (GFRP)".
I would hope there is a way to degrade, reclaim or reuse these materials.
Plasma gasification
Well, maybe, but don't these new tires use more rubber instead of air? In which case they will actually increase the amount of discarded tires? Also, what about the recycling potential of these tires?
I'm not an automotive buff, but this claim of being "good for the environment" sounds like just empty marketing talk.
In fact you can see that the photo of the EV on their site has sidewalls.
This is a tradeoff between environmental concerns and safety, as are most safety features on a car. We could make a car that gets insanely good milage and has little raw material, but it would be terribly unsafe.
I don’t see how these tires are immune to catastrophic failure that typically can take with it the rim and the suspension.
Have you? Your characterization of the experience makes me think you have not.
I have had two rear and one front blowout. Blowouts are just flat tires that have a loud intro before the typical "driving on flat tire" music. None of them were any more eventful than a normal flat tire. I'd take a blowout (or normal flat tire) over tread separation any day.
The internet highly highly highly highly highly overrates the danger, likely because blowouts are so rare these days and unfamiliarity tends to result in fear which compounds the Internet's tendency to reward certain commenting patterns. Other than the noise potentially causing a driver to incorrectly make massive control inputs (which would be equally hazardous to do after suffering a normal flat) there is no more hazard from a blowout than from a normal flat. And I say this as someone who drives old junk with fat sidewalls. On something with small modern sidewalls all the danger is less still.
Frankly, the one time I had a valve stem leak that caused a slow flat was much more unnerving as I initially wasn't sure if I was feeling things or if the vehicle was pulling to that side.
But yes, in many cases it just drags the car. None the less, it can cause huge issues.
Chicago or NYC would be much more of a proper test with potholes, humidity, potholes, temperature, potholes, and precipitation. Did I mention potholes.
(I'd guess they would overheat really fast if you drove them even moderately fast, plus the inertia would be pretty insane?)
update: similar questions here https://m.youtube.com/watch?time_continue=206&v=sc8ghIqKqnI&...
(I realize that video-phones are kind of widely adopted now via Zoom/Facetime/etc. - I'm thinking more of the vision from the 90s of a telephone with a screen in your kitchen)
Yes, I get that it might be hard for them to be separate.
But if they live up to the hype, it will be a game changer indeed.
Edit: apparently they are.
I think I'll need to instrument my car. If something like this works, it'll seem from the inside the gets heavier the faster it goes in addition to what clever airfoils and aerodynamic design already does.
Would that have any impact, f such tires would become popular?
Really? They cite a survey, but don't link to it.
12% of the tires that are discarded are discarded due to punctures or blowouts and 8% of tires that are discarded are discarded due to uneven wear caused by improper inflation.
I don't think that any advancement in materials or mechanical science can create a solution that outperforms the advantages of a standard pneumatic tire.
Given that I haven't seen tweels for bicycles yet, I assume the feasibility studies did not go well.
It also looks like they also announced that bicycle tweels were 'coming soon' nearly two years ago: https://jalopnik.com/bridgestone-says-airless-tires-are-comi...
Airless in this case means that they don't use pressurized air for rigidity, and therefore they do not need to be engineered to maintain air pressure, thereby reducing material input, and removing a major failure mode.
They are wheel-shaped springs.