I agree with Mark to an extent... I think people over do it a little, but if you are dead set on running rippers in a stock chassis, I think I'd start with a +12 over. I'm running a +10 up front +13 out back with my 14mm Cub with 12 paddle Haulers... I plan on doing some time and speed testing in Pismo, and Dumont in the next few months.