Road wear grows to the fourth power of vehicle weight. Vehicle land use may or may not be a problem (on the countryside it doesn't matter that much, in a histor

Road wear grows to the fourth power of vehicle weight. Vehicle land use may or may not be a problem (on the countryside it doesn't matter that much, in a historic part of an old city very much). I think ideally a rule that incentives smaller lighter vehicles thinks about both size and weight, with weight being the more important one by far.