Badd Dogg Guy19

Hey all, I just had 285 BFG KO's put on my truck, A few people have told me even with the minimal change in sizes, I should get the Speedo re-calibrated because It will help with the tranny shift points and also help with the ABS too.

My question is after the flash, will my overhead also re-calibrate for the bigger tires to help keep within mpg readings, or is it going to be off no matter what after you put bigger tires on and have the speedo re-calibrated??

I plan on having this done, and the High Idle enabled, and prob. my first oil change too, Would like to get everything done in one day since the Dealership I bought my truck from is about 45 mins. away from my house.

Thanks for any info

Str8Pipe

i called up mickey thompson when i bought 35x12.5x17's for the rpm's. went to the dealership and they recalibrated my computer. everything works fine now. cost me $20.

RamWheelsBy4

After you have the ECM reprogrammed with a correct "Pinion Factor" for your new tire size, everything will be normal as far as odometer, speed, ABS, trans shifts. The overhead will be as accurate as it can be. Mine was never accurate stock, after the reprogram, after the Flash or anytime.

Badd Dogg Guy19

Thanks for the info, I understand they change the "pinion factor" according to the revs per mile of the tire. Im going to print out the specs from BFG themselves and give it to the tech.

I understand the overhead will never be dead on. Ive had my truck since June, and I dodnt even have 3,000 mi. on her yet, Ive been averaging, lets say, 14.2-14.5 city, now its around 13.9. I do notice it takes a little longer for the trans to kick into O.D. When I'm on the Highway, I sometimes let off the throttle for a sec and it will drop in a little earlier than If I was to wait for it on its own. I do like how the RPM's are a little bit lower at 65mph.

I really wasnt gonna bother with the re-cal, but Being its a new truck, I want to do things right

Lightman

Badd Dogg - to answer your question - yes, the overhead will be corrected compared to before the pinion factor change. When I went up to my 35's my overhead mpg (which compared to hand calc was typically .5 off) went waay down...all of a sudden I was getting 10-12mpg... once I had it corrected at the dealer the overhead went back to normal too..