I have a 2007 f-150 XLT that came from ford with a odd tire size. it has a p255-70-17 and i want to put on p265-70-17 because there is many more tires to choose from. The tire shop told me that i need to take the truck to the dealer to have the new tire size programmed into the computer. they said if i don't have it done, it will throw off my speedo and can cause the transmission not to shift correctly. it could cause damage to the transmission. Does anyone know if this reprogram needs to be done? and what does the dealer charge for doing it. Thanks

 

You really don't need to do anything to the computer unless you go above 305 series, (35 in tires) the stock general tires are 31.6, 265 series tires are almost a true 32, the difference is not worth 50 - 100 bucks to get reprogrammed. your speedometer would only be off 2% or less.

 

I just put 265-70-17's on my 2007 F150 XLT and I paid one hundred dollars at the dealer ship to have the speedometer checked and adjusted. The speedometer was 5-6 mph off, as in to fast. I rather pay the money now than have a speeding ticket to pay. Do what you are comfortable with.

 

http://www.1010tires.com/tiresizecalculator.asp

you are effectively gaining 0.5" of total height. Your speedo will be off by 1 MPH


I'd do the size upgrade and forget about it. Besides, most stock F-150's come with 32" tires from the factory...which is essentially what a 265/70/17 is

 

I went from 255/65/17 to 265/75/17, which is a bigger change than yours, and my speedometer now reads correctly. My truck's speedometer read 2-3 mph faster than my actual speed with stock tires. I was told Ford and most other mfgs do this for legal cover. Going to a larger tire corrected this error.