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Do I Need To Reprogram?

jess7977

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jess7977 Enthusiast

jess7977

Posted
Posted

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 Senior Enthusiast

Wingnut

Posted
Posted

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 Enthusiast

Indy

Posted
Posted
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 Enthusiast

mattro

Posted
Posted
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 Senior Enthusiast

Ranger

Posted
Posted

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 Enthusiast

TBY

Posted
Posted
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 Enthusiast

chud53

Posted
Posted

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 Enthusiast

jess7977

Posted
  • Author
Posted

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 Senior Enthusiast

Ranger

Posted
Posted
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.

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