Im running the 4:57 gears with 33" tires. When i cross the line im turning at 6300 RPM. When i drop back down to my 32" tires, I was crossing the line at 6700 RPM. The only time i use the 32" tires is if i know the track is really going to hook up hard, the smaller tire gives me a better hole shot. ( 2 speed powerglide) My engine will still pull at that RPM, But i just prefer to keep the RPM's down to help save engine.