My friend who is a highway engineer would disagree with you. He says that roads will last a very long time as long as the shear limit of the road is not exceede

My friend who is a highway engineer would disagree with you. He says that roads will last a very long time as long as the shear limit of the road is not exceeded, but that once the maximum shear is exceeded the road will deteriorate. So, semis that do not exceed their weight limit are not a problem, but hauling a bulldozer around on a flatbed with four axles when it should have six will really do damage. It makes sense to me because my experience has been that when anything is operated within it's design limits it can last a very long time. So, unless the cars you are talking about have very narrow tires, I don't think they will be the problem you propose.