i wanted to do that with my old mod but then decided there was no point. yeah it would give you a bit more bounce as the guy above said, but it would add weight, look horribe, be a b**tard to set brakes up, you dont need nothing that big on the front, you use the back wheel to land on and there fore i wouldnt recomend putting anything larger than a 2.25 tyre on 20" rim.