How wide a wheel/tire can I go in 17s without having to roll the fenders or get any kind of rubbing on the inside plasitcs.

Turning of course.

 

It really depends on the wheel offset, suspension setup and alignment (camber). On stock setup, 255/40/17 without having to roll the fenders ... but there may be minor rubbing on the inside of the fender liner ... I've had minor rub with 245/45/17 during heavy cornering on stock setup due to the taller side wall.

 

Summer the wider the better
winter narrow= more traction

 

on the stock wheels you can go 255/40/17

 

some people run 17x10's around hear with 275 tires

 

NOT ON STOCK FENDERS!!!!!