I am going to get some BBS RK 18's in the plasma finish. They are 18x8.5 and 18x10. What size tires should I get? TireRack says to use 245/40/18 for the front and 275/35/18 for the rear. I want to keep the diameter the same so the speed/odometer are correct. Are there any other sizes that will not affect the speedo?
