I noticed that my truck has 265/75-16's and I don't know what the stock tire size was. The sticker from our door is ripped off so I can't see the tire info. I looked on tirerack.com and it says they're supposed to be 265/70-16's or 245-75-16's. I found a tire calculator online that shows these OE tires to be 30.5" On HPTuners I clicked on the speedo tab and it's showing my stock tune to have a 29.77" tire w/ 3.73 gears?? Is the tire calculator I found wrong or did someone input the wrong tire size into my PCM? Either way I need to update it b/c the tire calculator shows my 265/75-16's to be 31.6". Any ideas?
TIA

 

I don't own a Tahoe, so I don't know, but I would go with tirerack's recommendation - both of those tires are within .1" of each other.

Now, the tire you have is an inch taller, so yes, you should reflash your pcm with a proper value. In order to figure that value, read the following (which I also posted in another thread):


In order to truly detemine the correct setting to be used, you must measure the circumference of the tire in order to calculate the diameter value to be used (do not use the manufacturer value, it may be accurate, but it is not precise)

Two options in order to measure circumference:
1) Remove the wheel from the truck and use a flexible (cloth or plastic) tape measure around the center of the tire (with the tire at the proper air pressure)
2) or, the easier method (physically) and the one I prefer: With the tire at the proper air pressure, mark the tire and ground where they are in contact. Roll the truck, so that the tire makes 1 complete revolution. Mark the ground using the mark previously made on the tire. Take a precise measurement of the two marks on the ground - this is your circumference.

Divide the circumference by Pi (3.141592654) in order to determine proper tire diameter to use for programming.

 

265/70/16

Thats what was on my 02 Tahoe when I bought it.

 

Man your a hoe!!! HAHAHA JFWY

 

Thanks for the help guys. I just though it was weird that the stock tune is showing a diameter of 29.77 whereas tirerack and other tire size calculators show a stock 265/70-16 to be 30.5"