Your 275/60-17 tires are the exact 30" diameter of the 255/70-16 tires that Ford puts on the truck. They cannot possibly mess up the computer, ABS, speedo or anything else. The Goodyear dealer is full of crap, you don't need to know anything about tires to sell them.

 

Ditto, I have noticed there are alot of people out there and only a few really know what they are talking about. Find a good tire dealer and stick with them. They are far and in between.

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'97 F150 Lariat, Flareside, SC, ORP, 5.4, Mods: [i]305/70/16 GY ATS, AR Baja wheels, dual exhaust, Smittybilt nerf bars, fog light mod and Big Bird mirror toy.[i/]
kkirt1@hotmail.com

 

Sorry guys, here we go again. Just don't feel right after putting in the 265/70/17 tires with the new wheels. Firestone said it will not affect anything, Now the Goodyear dealer said take it off as soon as possible or it will mess up the speedometer, ABS and the computer. Then I checked with Tirerack and they suggested the same size I got on now. Which is kind of driving me nuts. And I notice some of our members are clad in 275/60/17 tires. Because I got the 30 days to test the tires and could bring it back for any reason I wanted to make sure I got the right size and not cause problems in the long run. Any suggestion,guys? Thanks.steve

[This message has been edited by MIF-150 (edited 06-30-1999).]

 

Strangeranger, I got the 265/70/17, not the 275/60/17 I wanted to get. The 265/70/17 looks 2" taller than the 255/70/16 that's the concern I'm worry about. I appreciate your input, anyone else can help? Thanks.

 

The 265/70-17 is 31.6 dia. About 5% larger than the 255/70-16 and 9% larger than the 235/70-16. Your mileage and speed readings will be off by that amount and acceleration will suffer as well. According to other posts on the list, your dealer can reprogram your speedo. A Superchip programmed for your tire size would solve that problem as well as give the performance the larger tires take away, maybe worth considering?

 

Strangeranger, thanks a lot, seems like you sure know a lot about tires and stuff. I went to the dealer this morning about the taller tires and he told me he don't know which speedo gear to sell me, plus no guaranteed it will correct it because they never done it before. You think I'm going to let these guys try it on my truck at 60.00 per hour and don't know what they doing? I don't think so, This afternoon at NTB I ordered a set of BFGoodrich CompT/A HR4 275/60/17 which is the same diameter as the 255/70/16, right? Anyone wants a set of Bridgestone HL 265/70/17 cheap? If not I'll just return it to Firestone.

 

Try a speedometer shop....

 

FYI
The formula for tire diameter is:

D=(T*0.0007874*A)+W

Where
D= diameter, expressed in inches, e.g. 30"
T= tire width, expressed in millimeters, e.g. 275
A= aspect ratio, expressed as a whole number, e.g. 60
W= wheel dia, expressed in inches, e.g. 17"

Hope this is of use

[This message has been edited by StrangeRanger (edited 07-08-1999).]