I need new tires and am thinking about goodyear silent armor. what is the largest i can go on 18 x 8 ford factory wheels. will 35x12.5 fit or is 8 inch not enough width

 

The tires will mount on that wheel but I am not sure you want to do it. The tires will not only look odd (ballooned) but they will not ride correctly and will probably wear in the center. The only way to alleviate this would be to air-down which would cost fuel milage and would not be safe at highway speeds.

I looked up that tire and couldn't find it in that size. The largest I found was a 325/60/18 which measures 33.4". This size tire calls for a minimum of a 9" wide wheel.

Hope this helps.