The point I was after to make is that you can't assume that road wear scales the same way as tyre wear (I was assuming same material fwiw, just different loads). They are being worn under very different modes/scenarios.
Given that roads and tires experience the same forces under driving conditions (Newton’s Third Law guarantees this) I think it’s a reasonable prior assumption to start from. There are of course other environmental factors that accelerate road wear (rain and water erosion, freeze thaw expansion) but those conditions were not included in the study that produced the Fourth Power Law.
