Quote Originally Posted by nfpgasmask
OK, I have seen a lot of comments about larger tires messing with the speedometer...soooooo, how serious is this? Like when it says you are going 40mph you are actually going 41mph or is it more serious than that?

Thanks - Bart
go here http://www.discounttire.com/dtcs/infoTireMath.dos
self explanatory