My dealer told me that he would recaliabrate the speedo for the 285's, that's great but what I really want is for the mpg's displayed to read right, mine says 14.5, I know that is wrong, it read 17 with the stock 245's, will recalibrating the speedo correct what the computer says? I'm not above selling these tires and getting some 265's to help out. Any tips. Thanks.

windermax,
Although I don't have 285's, from what I know and have read the dealer will only calibrate for the ABS to work properly, not the speedo, odo or tranny. You may consider getting a Predator, hypertech or something else along those lines that will recalibrate for tire size. Hope it helps.

LA DMAX

Thanks for the reply, maybe I should just take the $70.00 they wanted and put it in some smaller tires, don't really care to go with the programmers.

Check the posts under Tru-Speed calibrator. It is currently the only thing on the market that is going to get all the information correct to all your modules based upon output shaft speed information.

You wont rack up as many miles when the truck is calibrated to 245s. That probably 10% less miles when running the 285s! My edje attitude tells me my correct speed, which is about 5mph off at 65