My friend and I both just did the same mods to our trucks, his is an 02 and mine an 03. We did 6lb pulley, JLP CAI, and JLP diablo chip. The only other difference between the 2 is that I have a brand new set of 20in rims and tires on mine and he has the factory 18's and the tires are in great shape. The question is that I've ridden in his and it feels strong. From under 30mph he gets no traction whatsoever. Now in mine from under 30 it won't spin the tires, it just goes.. If you go from a stop it spins all of first but it pretty much did that when it was stock. It just doesn't "feel" as fast. So do the 20's make that much of a difference in rotating mass and traction?

-Sly

 

heck ya... it's not the rotating mass (well not only the mass) but putting a bigger size tire on the truck significantly changes the final gear ratio.

what size is the tire you have

 

it's a 295/40/20

-Sly

 

Must be the rubber or the wheel weight, not the diameter.

Stock = 28.5" diameter. 295/40-20s = 29.3. That's less than a 3% difference.