They do, but it is limited to different stock sizes from what I read.
Plus good luck finding a dealer willing to even try.

Huh. Well guess I'm wrong. Well either way 33"s aren't factory. So doesn't help much

Get a tuner, set the rev per mile on the tuner per the tire manufacturer spec/tire size.

I always triple check each vehicle I own via speedo, phone gps and a gps only unit (tom-tom, garmin...ect)


My truck, running 265/70R17's, actually runs 3 mph below the speedo reading.
Find out what your units say... average them out and use that... the heck with buying a unit to mess up your computer... never know what other problems it will screw up :) besides you will save money by not wasting your cash.


Just remember how much it is off, and don't go over :)


Of course this is just my opinion.... like so many others.....

My suggestion.. If you can swing it, buy an aftermarket tuner like I mentioned before, edge or SCT. You will be able to change your rev/mile so that your speedo will be correct AND the amount of fuel economy and power gains makes it well worth it in the end. My tuner has paid for itself probably 10 times over in the past 2 years of running it and I've only had 1 problem and it was fixed in an hour by a helpful tech support team.

That's fast for a truck, I'm proud to say I'm a member of the 200 mph club, 202 on a 2 mile airstrip. Charger hellcat, only mod was a cai and a mid muffler delete.

I think pcm has a setting for distance per revolution of tire, or diameter, and axle ratio

Ive seen it poking around in mine.

The pcm uses this to run engine too, not just speedo.. Small changes dont upset it. I would think 11% off would do something negative to mileage or power

Old thread.....just sayin.

been a lot of retreads lately

Yea, seen one from 06 just recently, that has to be a record lol.