I just got some new toyo 285-75-17's and would like to re-calibrate the speedometer. What is the best way to get this done? I understand the dealer can do it but only for 285-70-17 which would still be off.

Here is the MPH difference from Speedo versus GPS:

70 = 75.6
60 = 64.4
40= 43.5

the Speedo used to be dead on accurate with GPS.

BTW, I love the way the new tires ride and look (for the 24 hours I have owned them)

 

My understanding is the dealer can recalibrate your truck (04.5) for your 75 series tires. Just to make sure they have the right information, go to a slite such as this: http://www.miata.net/garage/tirecalc.html to make sure you have the size information and the revs per mile for the new tire.

I'm planning on getting the same tires you got whenever I can get the darn BFG's that came on the truck to wear out. I've got about 50K on them now...

 

Make sure you get your rev per mile information and then go to the dealer. You can normally get your information at the tire manufactures web site or the Dodge's Body Builder site. It is the 06 to present that tend to have problems with having the speedo recalibrated, since the last I heard it was not possible. Due to lack of DRB III programig parameters in the CAN - Bus ECM program on those trucks.

Shawn

 

I'm pretty sure the BFG website has the revs/mile number for each tire they sell. Find a comparable BFG tire and give the associated number of revs/mile to the dealer and they can program it into your truck for you. No need to tell them the tire size.