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.
In the UK a forty ton artic pays about a 1000 GBP per year for Vehicle Excise Duty (VED) plus Heavy Goods Vehicle (HGV) Levy. Cars pay different amounts based on emissions generally between one tenth and half what the biggest HGV pays. So the HGV is not paying anything like enough to compensate for the extra road wear.
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.
> So the HGV is not paying anything like enough to compensate for the extra road wear.
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.
> 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.
Not just class 8 tractors, either. Everything from (approximately) class 3 up (10,000+lbs GVWR, e.g., 1- and ¾-ton pickup trucks) is taxed by weight in some states (e.g., NC and VA) and taxes at a different rate (but not directly by rate) in others (e.g., FL).
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.
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.