What are the largest tires (width) that I can put on my 03 FXST (both rear and front) without doing any modifications. Thanks!

Hi.


Standard tires are already oversized in 03 model. This are the maximum standard allowed, probably the same as what you already have:
Front - D402F MH90-21 54H
Rear - D401 150/80B16 71H
(front: 80/90 - rear :150/80-it was 130 in 02 model)

Without modification you cannot use any bigger tire. By changing wheel, belt and pulley, you can mount at rear up to 200 at rear (see job done on the 06 softail here).

At front you need to replace wheel and to move the fender. The result is not always great when you do modification to front wheel. The best thing to do is buying a spacer kit.

Regards

Ginko.