max. tire size on 18's
 

i have an 03 coupe....what is the widest size tire i can put on my stock 18"x 8" rims without changing the ride height?....i currently have pilot sport 245-45-18 (rear) and 225-45-18 (front)

According to michelin's tire guide, 255s are the widest you could go.

The widest tire you should use, and still maintain the stagger is:

Front 245/40/18 - Rear 255/45/18.

The car will understeer less, and you'll have more neutral handling.

Lou