If they are torn it is an very easy fix and easy to weld them back together. Use a mig welder and just spot weld them back together right on the crack. keep doing continuous spot welds until the whole tear is welded back together. be sure not to get the metal too hot a good rule of thumb is if you cant hold your hand flat on the fender about 2 inches from the weld it is too hot.Let it cool and then continue. Grind of the excess but don't dig into the fender material and you should be just fine.