It would really help people help you if you gave more detail about where on the fender you want to trim, where the tires are rubbing, etc. I have 35" tires and have not had to trim the rear fenders. I did knock the front edge in a little to keep them from rubbing. Used a 2x4 and a hand sledge. There is not enough space behind the rear doors to do any trimming. I also cut the bottom chrome part behind the fender off to add sides to the bumper.