I just got new rims that are 18x8(F) and 18x9

 

I'd suggest doing the math to figure the sidewall heights. The ratio by itself doesn't mean much.

Keep in mind that sidewall heights are the same when you're non-staggered.

 

Sidewall height is a percentage of tread width and not a fixed number. For example, 35% of 255 will obviously be bigger than 35% of 225. You would want a 225/40 in front to match the 255/35 rear. Obviously if you are running same size width then you want the sidewall ratio the same.

 

[QUOTE=1nate7,Oct 1 2010, 10:15 AM]Sidewall height is a percentage of tread width and not a fixed number.

 

225/40/18 is the closest youre gonna get to the same ratio. Perfectly acceptable.

 

Nothing wrong with running smaller dia. tires in the front. Just know it will change the balance of the car and you may need to do some tuning to get the balance back.

Smaller dia. tires in the front will increase the cars rake, and in most cases increase oversteer. (may be a bad idea on a stock AP1)

 

Yes there is something wrong with running smaller tires on the front. It can throw off the anti lock brakes on the car. Anti lock brakes is monitoring the difference in the rev's per mile.

 

Good point about the ABS.
I have not had any trouble running 274/40 17 with 245/40 17 A6 Hoosiers on an 2004 and 2008 S2000. At least the AP2's seem to handle different size tires well, but you are right that it could cause problems.

 

Thanks everyone for the information! Looks like I will go with a 40 upfront and 35 in the rear.

Also, can you run a 265 tire on an 18x9+50 rim?

 

[QUOTE=Lex,Oct 1 2010, 12:21 PM] Thanks everyone for the information! Looks like I will go with a 40 upfront and 35 in the rear.