Grant:
KMM:

Grant, I have a question regarding tire wear in the center. Is it a sign of overinflation (causing the tire to "balloon", i.e., to be more round, resulting in more contact and wear in the center)? Or is it a sign of underinflation (causing the tire not to be "stretched" properly, allowing it to balloon at high speed instead of the contact patch remaining flat)?

I used to assume the former, but I was told years ago that it was, counterintuitively, the latter.

I believe that under-inflation wears the shoulders and over-inflation wears the center.

 

That's always the case, because science. 

Sidewalls are always stiffer than the flat part, so for under inflating tires, the sidewalls will be what's supporting the car, hence the shoulder will be wearing quicker for under inflated tires. 

Over inflating will balloon a tire, again the side wall is stiffer so they would bulge much as compared to the contact patch so the centre will always goes first. 

One reason why EVs have higher than normal tire pressure, they want the centre to bulge out some what to minimize the contact patch and minimize friction. On top of EVs being generally heavier and needed more support. 


--