Speedometer question

[Devildog]

Is there any way to calibrate the speedometer after install larger tires, My speedO is out 6-7 MPH after install 35"(315) tires. The dealer says their equiptment will only calibrate the computer to 285 tire size. Thanks.

 

[Newf Limo]

I could be wrong, but isn't a 235 the same height as a 265 as a 285??? What calibration would they be making?



On older vehicles there was a gear at the end of the speedo caple and you could get different gear sizes to help match different tire size. If you have 4:10's in the diffs. you could find out what your effective final drive is now (i. e. 3:73, 3:54) and make the changes that Dodge would make for changing rear end ratios. I am just shooting in the dark though. Someone hear can give you the formula for figuring out your effective final drive and I am sure someone has a fix. Hang in there.

 

[DEZLPWR]

Get the Abbott Speedometer Recalibration Module!

I have it on my truck with my BFG 35"s. The speedo is dead on. I got it thru Jannetty Racing. Approx. $130



See my signature below.



Steve

 

[work2muchplay2little]

You're in luck, I just posted this last week If you have 4 wheel anti-lock brakes, I'd give Rickson's a call (check the links page).



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=22253