Want bigger tires, need to reprogram?

last truck · September 1, 2016

I would like to stay leveled but want a 32.6 inch tire, so will I have warning lights and nastygrams in my message center if I don't reprogram the truck for them. I know my speedo will read a little slower but that I can deal with, setting ABS codes I can't, so for everyone whose is running mildly larger tires did you reprogram or not and if not are you setting codes?

thanks

JeremyW426 · September 1, 2016

what size tire is on your truck now? My stock 20's are only 31.9" tall and to go to a tire that's 33" tall will only set my speedo off by 3.4% (at 50MPH on speedo, will actually be 51.7MPH) you're truck will never show you a warning message for changing the size of tire, there's just no sensors for that. Throw the tires on and you'll be fine.

Check out this link if you want to compare your current tire size to the ones you want to put on. https://tiresize.com/comparison/

FLHRSI04 · September 1, 2016

nope you won't have a problem

last truck · September 1, 2016

what size tire is on your truck now? My stock 20's are only 31.9" tall and to go to a tire that's 33" tall will only set my speedo off by 3.4% (at 50MPH on speedo, will actually be 51.7MPH) you're truck will never show you a warning message for changing the size of tire, there's just no sensors for that. Throw the tires on and you'll be fine.

Check out this link if you want to compare your current tire size to the ones you want to put on. https://tiresize.com/comparison/

Right now it has 265/65R18;s that are 31.6 inches thanks for that link.

Vikes · September 1, 2016

I used hypertech speedometer calibrator, was really easy, just measure diameter of tire and program, checked it with GPS and it was right on.

TJay74 · September 1, 2016

what size tire is on your truck now? My stock 20's are only 31.9" tall and to go to a tire that's 33" tall will only set my speedo off by 3.4% (at 50MPH on speedo, will actually be 51.7MPH) you're truck will never show you a warning message for changing the size of tire, there's just no sensors for that. Throw the tires on and you'll be fine.

Check out this link if you want to compare your current tire size to the ones you want to put on. https://tiresize.com/comparison/

Just a heads up, GM uses the same tire height in all of the calibrations no matter if the tires are 17", 18" or 20" on the K2xx trucks. As long as you run the same size tire on all 4 corners you wont have any issues with the ABS system. If you vary the tire height by 1" or more it will trip out the ABS computer and throw codes. I doubt we will see this on the trucks, but on GM cars that run staggered front to rear wheel/tire setups it can cause issues.

Case in point the 2005+ Corvette uses 18" fronts and 19" rear wheels, the tire heights are different for the front and rear of the car, but the ABS computer is programed for that. As long as you ran stock size wheels and tires you were fine, some owners went with wider rear tires and ran stock fronts and it would trip the ABS computer out due to the variance being more than 1" from stock.

cato · September 1, 2016

I ran 33's last year. No issues at all. Never even bothered to recal speedo either. Really no reason to IMO.

You'll be fine.

JeremyW426 · September 1, 2016

Just a heads up, GM uses the same tire height in all of the calibrations no matter if the tires are 17", 18" or 20" on the K2xx trucks. As long as you run the same size tire on all 4 corners you wont have any issues with the ABS system. If you vary the tire height by 1" or more it will trip out the ABS computer and throw codes. I doubt we will see this on the trucks, but on GM cars that run staggered front to rear wheel/tire setups it can cause issues.

Case in point the 2005+ Corvette uses 18" fronts and 19" rear wheels, the tire heights are different for the front and rear of the car, but the ABS computer is programed for that. As long as you ran stock size wheels and tires you were fine, some owners went with wider rear tires and ran stock fronts and it would trip the ABS computer out due to the variance being more than 1" from stock.

Generally, that is correct, however, there were certain variations of 1500 base model trucks that came from factory with a 255/70R17 tire on them, with my 20's (275/55R20) there is actually a 2.6% difference in height. To go from a 255/70R17 to a 33 there is a 6.1% difference in which case I would then start to consider a programmer. I do admit that would be a rare case being its not as common.

tenscourts · September 2, 2016

You're going up an inch which is 3.2%. I recently went from a 275/55/20 to a 275/60/20 which was a 3.4% increase and I have no issues at all. I was ready to buy the calibrator and the guy told me not to waste my money unless I went up to a 35 inch tire (which I don't plan to do). Also if you're still under warranty that calibrator is considered a programmer and although it shouldn't cause warranty issues you could end up with a fight on your hands should something go wrong.