I just put on some new Toyos size 285 75 r17. I have an 03 with 3.73 rears,nv 5600 tran, I was running 33 12.50 r 17 how much will this affect my speedo plus-minus,and how do you calibrate the speedo ??

 

Your speedometer will show you going 3.5% slower than you actually are. In other words, if your speedo shows 50, you are actually going 51.5 mph. The factory can recalibrate the speedo for you. They told me it would cost $80 for the flash. I have the same tire size. I figure it is not enough to worry about.

 

It's not really a flash, It's just a matter plugging in a DRB3 and setting the pinion factor. If you got a friend who is a Chrysler tech, he could do it 5 minutes.