Question? I have a 05 Hemi ram with the 3815 AND LOVE IT! However I switched over from the stock 17inch wheels witht the stock tires to a set of 18*9.5 wheels with 285/60/18 tires.. My question is. My superchips tire setting now is on 30.75 for the stock tires. QUESTION should i measure the new tires while they are on the truck under the weight of the truck or should i take a wheel and tire off and measure it with no wieght on it. I measured one under the wieght of the truck and it was 30.25. thanks.. SUPERCHIPS KICKS *h! love the 2nd gear chirp!