On an 07 tahoe you will need a 6 inch lift to fit 30s with 315/30/30. Pirelli is coming out with a 315/30/25 which will save you maybe 2 inches of lift, but not many people like riding on rubber bands. Reason you need such a large lift is you cant exactly cut the rear fender due to the fact that one half of it is actually the back door. Good luck.