Hey everyone just wanted to get ya'lls thoughts on this. I put on my K&N FIPK and went from 265's to 285's in the same day and have almost run through my first tank of gas. As it stands now it looks like I'm going to get between 60-80 miles less off this tank than I have always gotten before the mods. Now in YHO is the difference bad milage from the bigger tires? Or am I just covering more distance with the bigger tires than my odometer is reading because I haven't gotten it recalibrated for the bigger tires yet. Or is it most likely a combination of the 2? I haven't done the exhaust yet because I'm still trying to decide what I want.....like I read in another post I wish they would let us try them out and return the ones we didn't want hahaha

i would guess that it is the tires size difference that is causing this. my spedometer is off by 5 at 65 and off by 2 or 3 at 30. and in a whole tank it throws it off by 70-90 miles on a tank.

so you don't think i'm actually getting worse milage then? it's just the fact that my odometer says i've gone 300 miles when in fact i've gone closer to 380?

I HAVE THE 285 75 16S AND MY MILAGE IS OFF BY 6.5%

drive a set milage and record distance
then drive in a nother car with stock tires and record distance

then compare

Go to the discount tire site and they compare tire sizes and you can see the difference in distance travelled. Then do the math.

I bet you have been gassing it a "BIT" more with the new intake :iceslolan :naughty: :lol2: :eek: Right????? :nono:

I bet you have been gassing it a "BIT" more with the new intake :iceslolan :naughty: :lol2: :eek: Right????? :nono:


I've been actually pretty proud of myself. I've been a "good boy"......for the most part. But I have to admit that I just love the new sound of the engine when I open her up a little lol.

Hey everyone just wanted to get ya'lls thoughts on this. I put on my K&N FIPK and went from 265's to 285's in the same day and have almost run through my first tank of gas. As it stands now it looks like I'm going to get between 60-80 miles less off this tank than I have always gotten before the mods. Now in YHO is the difference bad milage from the bigger tires? Or am I just covering more distance with the bigger tires than my odometer is reading because I haven't gotten it recalibrated for the bigger tires yet. Or is it most likely a combination of the 2? I haven't done the exhaust yet because I'm still trying to decide what I want.....like I read in another post I wish they would let us try them out and return the ones we didn't want hahaha


You need to pay the dealer a visit and have them program your new tire size into the PCM with the GM Tech 2 scanner, and then your mileage reading and speedo should be accurate, since then the truck will know what size tire it's dealing with.

what should a stealer charge to reprogram the speedo?? since it probably takes all of 2 minutes or so. i am sure they charge like 200 or so. you might as well go buy a hypertech or get a nelson tune and have him set it.

what should a stealer charge to reprogram the speedo?? since it probably takes all of 2 minutes or so. i am sure they charge like 200 or so. you might as well go buy a hypertech or get a nelson tune and have him set it.


When I worked at a dealership, if you bought the truck from us, we'd do it for free. Otherwise it's usually around 50 bucks or so.

I just went from 245`s to 265`s on my 99 Silverdildo and my mileage seemed to go down by 1-2 mpgs.

My speedometer was exactly 5 mph off at 65 mph,as someone previously stated. Now its right on with my GPS.

Seems to me like you should get better mileage with higher profile tires,but since your speedometer is always off,unless you reprogram the puter for each different set of tires,its hard to make that determination.

It also takes more work to get and keep taller tires rolling.

what should a stealer charge to reprogram the speedo?? since it probably takes all of 2 minutes or so. i am sure they charge like 200 or so. you might as well go buy a hypertech or get a nelson tune and have him set it.

The dealer here said it would take 30-45 min and would cost about $40. I don't know if I'll go and get it done or just wait until I get my Nelson in feb.....