Why?





What does this do?

This will correct your speedo and set your shift points right based on the new tire size. The larger you go over factory the more everything will be off. Same goes if you change gear sizes.

However you must get an aftermarket programer to do the correction. GM will not give out numbers for anything over 265/75R16 due to warranty issues. Trust me, I tried and was flatly refused. This is just in addition to what Chevyfreek said.

My speedometer is only off about 4 miles an hour at 70 according to my GPS, is this critical to the ABS?

That mean's you're out only 5.7%. That's not too bad. I'm out by about 13% on mine and I haven't run into any problems as of yet! Keeping my fingers crossed. Odometer says 23K (actual is 26K) now and not a blip out of ABS!

My speedometer is only off about 4 miles an hour at 70 according to my GPS, is this critical to the ABS?


ABS should be fine unless you get the warning light like I do.