right heres what i have done. took a 2.5 maxxis off the front and replaced it with a 2.1 tioga, which has saved a lot, but its the rear which is the tank of the bike it is a ton weight, i have a 721 on hope xc and an echo tyre with a dh tube in, is it safe to drill the inside of the rim? i stil ride street on it but its like sidehops and lots of front bumps, and gaps like compy street.