Do I Need To Reprogram?

[jess7977]

I just put some 265/75R16 BFG AT'S on my 2000 4X4 Silverado SB RC with 3.73 ratio. It came from the factory with 245/75R16. Is the difference in size so drastic that I have to get the PCM reprogrammed? And if I do, is there a fee involved at the dealer? Does anyone know the cost? Thanks for any info in advance.

[Wingnut]

Yes, it's a good idea to have it recalibrated. The dealership should be able to do it, but were I in your shoes, I'd get an aftermarket mail-order tune. Tire size can be corrected for, you'll get better mileage, and more power to boot.

[Indy]

Yes, it's a good idea to have it recalibrated. The dealership should be able to do it, but were I in your shoes, I'd get an aftermarket mail-order tune. Tire size can be corrected for, you'll get better mileage, and more power to boot.

 

I agree with Wingnut, get a tune.

265/75/16 is a difference of 3.73% which in tires is significant. 265/70/16 would be only .46% and a recalibration would not be necessary.

[mattro]

Yes, it's a good idea to have it recalibrated. The dealership should be able to do it, but were I in your shoes, I'd get an aftermarket mail-order tune. Tire size can be corrected for, you'll get better mileage, and more power to boot.

 

I agree with Wingnut, get a tune.

265/75/16 is a difference of 3.73% which in tires is significant. 265/70/16 would be only .46% and a recalibration would not be necessary.

 

 

guess i need to get mine done. I have 3.73 gears with a posi rear. its 245/75/16 on the door but when i bought the truck it had 265/75/16 its tops out at only 98mph so im guessing he didnt have it recalibrated. And sad gas milage id say for a 4.3L 5spd

[Ranger]

A stock PCM will top out at 98 mph no matter what tire size you're running. But you may be going faster than 98 in reality. I have 285/75r16s on and my speedo is usually off 5-7 mph at 60+.

[TBY]

I just put some 265/75R16 BFG AT'S on my 2000 4X4 Silverado SB RC with 3.73 ratio. It came from the factory with 245/75R16. Is the difference in size so drastic that I have to get the PCM reprogrammed? And if I do, is there a fee involved at the dealer? Does anyone know the cost? Thanks for any info in advance.

 

 

but if you were to get a speeding ticket you can get out of it by having it recalibrated before you go to court

[chud53]

good to know, im in the same boat as Ranger. My mph is usually off the exact same, i think i need to have my speedo recalibrated, and new gears and that should get me back to around stock MPG, torque, and power. What gears should i go with 4.11 or 4.56???

[jess7977]

Thanks for all the info guys. I have been wanting to buy one of those hand held programmers for a while. Now I have an excuse.

[Ranger]

good to know, im in the same boat as Ranger. My mph is usually off the exact same, i think i need to have my speedo recalibrated, and new gears and that should get me back to around stock MPG, torque, and power. What gears should i go with 4.11 or 4.56???

 

If you still got 35s on, 4.56 will give you equivalent gearing of 3.73 I think.