If you're wondering, here are some tire sizes that come close to matching the Evo X spare tire, so that you don't blow diffs if you're paranoid. Some sizes are included even though they are impossible to find and frankly quite ridiculous but they equal the height of the spare tire. I blew my tire on a pothole this year and got the 4WD Service Warning once my car started going crazy with the uneven sizes.

Spare: 145/70/18, height 25.99213 inch
Stock: 245/40/18, height 25.71654 inch

Winter Tire Size: 225/45/18, height 25.97244 inch
Winter Tire Size: 215/35/20, height 25.92520 inch

Summer Tire Size: 255/45/17, height 26.03543 inch
Summer Tire Size: 285/40/17, height 25.97638 inch Would be my preferred if I could find a 17 x 10.5 wheel that cleared the front Brembos.
Summer Tire Size: 255/40/18, height 26.03150 inch
Summer Tire Size: 285/35/18, height 25.85433 inch
Summer Tire Size: 255/35/19 height 26.02756 inch
Summer Tire Size: 295/30/19 height 25.96850 inch
Summer Tire Size: 255/30/20 height 26.02362 inch


Ridiculous Tire Size: 405/25/18 height: 25.97244 inch
Ridiculous Tire Size: 675/15/18 height: 25.97244 inch
Ridiculous Tire Size: 355/25/19 height: 25.98819 inch
Ridiculous Tire Size: 305/25/20 height 26.00394 inch

 

Anyone worried about causing damage from driving on mismatched tire diameters can (and maybe should) just pull the fuse to the ACD/AYC pump. If the diffs are open (and you drive calmly), nothing bad can happen. You shouldn't be engaging the ACD or AYC on the donut spare, anyway.

ps. where can I get a widebody kit for the 675/15/18s?

 

I think 255/40/18 and 225/45/18 are sensible tires to drive on the street with and hopefully not trip the AYC/ACD too much.

Amazingly 305/25/20 are almost spot on for people who want lotsa tire, lotsa wheel and can rock a donut if need be.

 

The best single piece of advice is to put the odd tire in the rear. The rear never locks in a 1:1 ratio, but the front does. Plus, we have a front-heavy car.

 

Can we fit a 17x10.5" wheel and a 285/40/17 tire on the Evo X? Or do all 17's have trouble clearing the Brembos?

 

Every now and then someone posts that a certain 17" wheel (often some Rota) will clear our OE brakes. But I've yet to see pics, so, by internet rules, it didn't happen. And, to be blunt, I no longer really care. (I sometimes quote Shrek when looking at the OE Brembos ... "do you think that he's compensating for something?")