I am thinking about putting new tires and wheels on my 98 GT. Right now I just have the stock wheels on and 255/45/r16 m+s tires on. I would like to get some decent street tires (something that is good in all weather since I live near Seattle) and I would like to go up to maybe 18's and would like something just a shave wider. What is the widest wheel and tire combo that i can install? Also the car is sitting at stock ride height, which it might stay that way, or drop about an inch.