barneyz71

I am getting new tires on my 2012 F150 that are 275/60/20 stock is 275/55/20 and the dealer is saying they cannot correct the speedometer! Has anyone had this done or is my dealer correct?

EdCaffreyMS

I would say that the dealer is correct. I tried going from 275/65/18s to 275/70/18s and my dealer told me that unless the tires are a size that comes stock on the truck(s) from the factory, they could not calibrate the speedo.
After thinking about it, my opinion has become that it's probably best all the way around to stay with the factory size tires....these new trucks are so integrated, it's unreal. Changing a tire size, without re-calibrating effects much more than the speedometer....it will essentially impact the entire truck.

KingRanch4Life

iTrader: (2)

I've been eyeballing this thing for some time now... The dealership won't re-calibrate... and that's the suck part...

http://www.autoanything.com/performa...A3757A0A0.aspx

SVTF150

This Hypertec programer works great! If you sell your truck, return the speedo to factory default with the programmer though. It is only good for one vehicle at a time, and becomes an expensive paper weight if you don't do that. I am the proud owner of an expensive paper weight because of this!

jarrett

The overall sizeof that tire is 32.99 inches. This is also the size I am looking at because I would like a true 33 inch tire when its time. The way I understand the recalibration is they can only recalibrate to certain preprogrammed sizes. But, if there is a programmed sized tire that is closer to that 32.99" than your factory size. It can be switch to it. They do not have to program your exact 275/60/20 into the computer it just has to know the size in inches for revolutions and such.

barneyz71

Well they managed to wreck one of my wheels while installing the new tires. They are going to order me a new one. It's the 20" chrome clad! Anyone know what that wheel is going to cost?

Mlarv

If they wrecked it then they should be paying for it. But if you go to www.tascaparts.com you will be able to get a price for it and just about any other part you want for your truck.

barneyz71

Yes they are paying for it. I just wondered how much it was going to cost them.

smokeywren

That Hypertech speedo calibrator works only on the 6.2L engine. No mention of the 3.5L EcoBoost, 3.7 V6, or 5.0L V8 engines.

Similar products are made by Pro Comp Accu Pro and SuperLift TruSpeed, but they won't work on 2011-up F-150 engines either.

Ford changed the software for speedo calibration around 2006 or so, and most hackers haven't yet figured out how to calibrate the speedo for other than stock-size tires.

So before you buy a speedo calibrator, be certain it's guaranteed to work with your current engine. If you find one, then please come back to this thread and inform us all.

Ford engineers don't like shade-tree mechanics changing to non-standard tire sizes, so they make it difficult to calibrate things when you do.

Here are the stock-size tires for 2012 models, listed from the shortest to the tallest. Most of these sizes are are applicable to earlier F-150s back to about 2009.

Tire size....... tire revs/mile
P255/65R17 = 691
P265/60R18 = 685
P235/75R17 = 674
LT245/75R17 = 658 (heavy duty payload pkg)
P265/70R17 = 654
P275/45R22 = 654 (Harley Davidson)
P275/55R20 = 652 (Platinum)
P275/65R18 = 648

Additional sizes used for the 2009 models include:

LT245/70R17 = 693
P235/70R17 = 681

The smaller the revs/mile, the taller the tire. The speedo/odo/tripmeter software uses the revs/mile parameter instead of tire diameter or radius because revs/mile is more accurate. So if you want the Ford dealer to be able to calibrate your speedo for new tires, be sure thay aren't taller than 648 revs/mile, nor shorter than 691 revs/mile.

The tire revs/mile is included in the specs for most major brands of tires.
Note that the popular 35" diameter has about 600 revs/mile. So if that's your tire choice, then the Ford dealer probably can't get closer than 648 revs/mile, which is still about 7% speedo error.

smokeywren

Dealer cost is about $561. Tousley Ford sells them for $623.49 each, which is 10% over cost.
http://www.tousleyfordparts.com/part...layCatalogid=0