How good are American roads?

> Interestingly, in all cases urban roads are worse quality than rural roads, presumably because they see higher traffic than rural roads.

There's more infrastructure under urban roads. Crews come in to fix some utility, shred a section of a lane, patch it poorly with dissimilar materials, and leave.

You're probably also going to have far fewer massive vehicles on those rural roads. More things like pickups yes, but probably considerably fewer semi-teicks and busses and fire trucks and cement mixers what not. Those big trucks passing through are going to stick to interstates far more often when going through rural areas.

We have large farm machinery though.

There is large machinery. But does it go down the same stretch of road 20 times a day all days of the year though? May also depend on location. You ain't taking the combine down the road several times a day in the middle of winter. So you do get the wear and tear of large farm equipment, but its still probably less than an urban road and not year round.

Also their slow speeds and larger tires probably lead to less wear than another vehicle of the same weight traveling at normal highway speeds.