18-wheelers already pay taxes very differently than consumer cars. I don't know how much higher they actually are. Maybe someone with knowledge can weigh in here.
A typical medium sized car weighs about 1 600 kg and has two axles, so an axle weight of 800 kg. The artic has six axles and weighs 41 000 kg, 6 833 kg per axle. The artic has over 5 000 times the effect on the road.
Do your road repair money not come from fuel tax on hundreds of liters of diesel per fill?
I can see this becoming an issue for EV's but that can be fixed by taxing mileage and weight. Though the mileage part is tricky as its going to be a cat and mouse game of fraud and privacy concern.
It's not a privacy concern. The mileage is already recorded as part of the periodic safety test, annually in the UK, every two years in Norway (and the rest of EFTA I think).
> Do your road repair money not come from fuel tax on hundreds of liters of diesel per fill?
No that goes into the general treasury funds, as far as I know. It's about 0.60 GBP per litre in the UK. Typical fuel economy gives about 3 km/l so a tax of 0.20 GBP per km.
UK HGVs travel about 25 x 10^9 km per year so the income is about 5 x 10^9 GBP/year. The UK spends over 11 x 10^9 GBP per year on roads, mostly maintenance, more than double the income from diesel fuel duty.
Rates for each state are available through their respective DMVs. Max-weight rated class-8 trucks (overweight is handled by by-instance permit, not registration) are 80,000lbs, and they are not cheap anywhere that I'm aware of.