I have to agree with Graham. I don't think tyre wear is effected in anyway by what you have the difficulty setting at.... unless there is a setting to turn the tyre wear off completely, but i don't think i've seen that.
Even that I am not sure about. Do they become unavailable at lower levels? Or is that just that game bug where they are not available if you select amateur for example. But you will get them back if you select Legend, then customise Legend down bit by bit (each setting) to amateur levels.
There are no settings to change the tyre or fuel simulation in the xbox version of this game, neither in GP mode, Career mode, or online Custom race. The only thing you can turn off is car damage.
Does that include the tyres?!?!?!.... I don't know LOL
That correct on PC too. There is no option to disable tyre or fuel sim, however some users were having problems, and I think it all stems from the 2 day driver tests at the beginning. If a lower level was selected after the tests, for some reason when they played the fuel and tyre selection you get on the quick menu when driving was greyed out and couldn't be used. Brake balance was OK
Mostly this could be fixed by selecting the default Legend setting (none of the others), then changing the ai strength down and adding any assist that you want to use individually, ending up with the game at the level you wanted to play at. Then the fuel, tyre (and brake balance) quick menu item worked correctly.