question...when a dealer does a spedo recal, can they input practically any tire size? I know the rear end (gears) and tranny only has choices that were available for a particular VIN #. Looking at 275-70-17 or 285's to slow speedo down just a bit. Currently have 265-70-17. If not, i guess i'll have to bit the bullet with a tuner. thanks...........rossford 2005 scab

 

yes they can calibrate your gear/tire size on your year of truck. The cant do older they couldnt do mine exactly the were able to get it closer..

 

Yes they can calibrate, but are limited to certain tire sizes. Those that were options on the vehicle. In your case, if you go with 275/70R17, you can have them input 275/65R18, which is exactly the same diameter as the 275/70R17. That is what I had done when on my 07 I went from 235/75R17 to 275/70R17. Also I believe as far as gear ratios, they are limited to those that are options on the vehicle.