Larger Tire/REVS per Mile reset

[GOLIATHGMC]

Just installed the Larger 315/70-17 Goodrich A/T's on her '06 with 1009mi on the clock. Makes the truck look BIGGER and BEEFIER - she loves it. My problem is that I need to change the Revs per Mile value so the speedo & ODO read right - and neither of my scan tools will do it. Local dealer wants $75, and the dealer where we bought it wants $93!@#$%. I simply refuse to light my money on fire like that - 1 hours labor for 3 minutes work. :{ Anyone have a better idea? Anyone within a 2hour drive of NYC who can help? (we would be more than happy to spend the money on dinner or coffee or whatever - better than the GREEDY pocket of a Dealer). Thanks!

GOLIATHGMC

 

[Spooled-up]

You could invest that money you would have spent at the dealer and get a Smarty that will adjust the tire height through the OBDII port.

 

[JCleary]

Well, the dealers in your area aren't going to be successful even if they try.



Up to '05 they were able to access the ABS computer with the DRBIII and change the revs per mile to whatever you wanted.



For the '06 trucks there is a new tool called a Star Scan (or something similar) that will allow you to pick tire sizes from a menu, the largest being the 285 that comes on the Power Wagon. It's about a 33" tire.



I guess the best thing to do if you're worried about your speed is to get a GPS and leave your setting at the 265 tire size. At least your warranty will last longer.



According to several techs I've communicated with, there's currently no way around this. It was something I researched while looking for an '06 Laramie auto. I decided to keep my '03.

 

[betterthanstock]

For the '06 trucks there is a new tool called a Star Scan (or something similar) that will allow you to pick tire sizes from a menu, the largest being the 285 that comes on the Power Wagon.

I have an 03, and I put 315's on it in april 03. The dealer did not know how to change tire revolutions, but they changed to the 285's (they wanted $50, but did it for free since I had a computer reflash/TSB at the same time.

The odometer is off by 5. 8%, so when I calculate miles I multiply by 1. 058.

The stock needle usually reads 1 mph too high for liability reasons, so it's not too far off, 1 mph at 25, 2 at 50, 3 at 70. (so it cuts the difference in half over what you have now)

You can try bargaining for a half-hour rate if you get an oil change or some other stuff.

 

[RMadgar]

I know your problem. When I put my 35x12. 5x17s on it took 5 trips to the dealer to get it right. I also have an '06. They did not even charge me because I was the test mule for the tech. He got tired of pulling the truck around a he just came out to the parking lot with me and we tried different sizes in the Star Scan tool. I tested it against my gps. I ended up finding my true tire size (34. 7 inches) and a tire calculator online that converted it to 265x85x17. The Star Scan let him program this in and all is well. To get your 315x70x17s (34. 4 inches) close, you can either try that number or try 275x80x17 (34. 3 inches) or better yet 295x75x17 (34. 4 inches). I can't remember if he said the Star Scan would read over 285 or not.

 

[Doughboy21kd]

Anyone know what the number would be for 33 x 12. 5 x 18..... I wanna have my speedo corrected?

 

[RMadgar]

From what I can remember of the Star Scan maximum settings, 275x70x18 (33. 2 inches) would be as close as you can get. The 18 inch rims are awkward when you convert them. This is the tool I use to convert sizes: http://www.miata.net/garage/tirecalc.html. Hope I helped a little.

 

[lcaad1249]

315/70/17's make the stock truck 12% off meaning you multiply by 1. 12 to get an accurate count. If trying to find out the speed a quick and pretty close way I've found to get a close speed is to take the first the second digit and add it to your speed (ex. 65+6=71, 72+7=79) Plus you don't put near as many miles on your truck.

 

[GOLIATHGMC]

Thanks for all the replies - I really appreciate everyones input. I am quickly realizing that the dealer may indeed be the only answer here.....

I just got the latest issue of DIESEL POWER, and in it there is an article about the new Hypertech HyperPAC programmer - something I saw an ad for in the previous issue and really liked. Among the list of things this unit is capable of is a tire calculator that will correct for larger tires. HOWEVER, the DP testers admitted that they were having trouble making it work right. They were using it on a brand new Duramax Chebby. I am amazed that with current computer technology, it is so difficult to make this VERY SIMPLE change.

Thanks again everyone

GOLIATHGMC

 

[lcaad1249]

I think Superlift makes a speedometer calibrater to. I don't know anything about it, but another option to check out.

 

[Tacsavage]

Unruly, my little brother, has 40's on his 06' 2500 and spent $100 dollars on handheld gps and mounted it on the dash. Looks pretty cool and is functional. Plus when he puts his 35s on no problem. Tac