Speedo Correction (1 Viewer)

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Rixeyville, VA
Just picked up the 80 with its new ome heavy lift and 285's( i will try to get some pics up soon) and i love it. totally worth the money. but my question is...going from 275' to 285's, will that mess up my speedo that much? maybe like 2 or 3 mph?
 
Your speedometer and odometer are off approximately 6%. The exact amount depends on the circumference difference between the two tyres.

Christo sells a correction gear that replaces the stock gear. It is very easy to install and cheap. With 285's, my speedometer was exactly the same speed as measured with a GPS.

-B-
 
I remember the literature that accompanied my Truspeed Recalibrator stated that 'stock' speedos can be off as much as 10% . I would suggest you do a quick hwy run with a gps , and see what you get . Sit it on the dash , and set the cruise to 60 mph .. and see what your true speed is on the gps , and then do the math as to your % error . I imagine as Beo stated that the gear would be more than sufficient .


TY
 
Do a search - plenty of info on this. As B has stated easiest solution is Cristo's speedo gear. Very simple swap out. If you want perfect accuracy then the Truspeed is the other option, tho more expensive and more complicated to install.

As I recall using GPS with stock 275's, speedo 60, GPS 57-58 I think. With 285's b4 speedo gear swapout, speedo 60, gps 62-63. With gear correction, I'm now pretty much 60-60. Every truck will be a little different.
 

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