Originally Posted by YUN
Can I mount 40 tall tires like 18 factory's size? Otherwise it defeats the purpose of having 18's and put on 35 and 30 rubber on it.
It depends on what width tire sizes you end up wanting on the car. With the e9x M3, most people want a tire that is at least 265 wide, which would require a 35 sidewall since the 40 sidewall would be way too tall due to width of the actual tire. Keep in mind, the tire sidewall profile is an aspect ratio
, which means it is a percentage of the tire width, thus the wider the tire, the smaller of a sidewall profile needed. For example, a 245/40/18 Hankook RS-3 has an overall diameter of 25.7", and a 275/35/18 Hankook RS-3 has an overall diameter of 25.6", a total of 0.1" difference in diameter.