taller tire, recalibrate speedometer?

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Joined
Aug 23, 2005
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Marble Hill, MO
hoping that someone out there can answer a question for me. just had 265/75/16's put on my 01 ST. had 255/70/16's on it. was told that i would have to have the speedometer recalibrated. does anyone know if i really HAVE to do this? :unsure:
 
"HAVE TO?"



"You don't have to. This isn't Russia. This isn't Russia is it Danny? No, I didn't think so!"



But, seriously, others here have reprogrammed their ST due to mounting of smaller/larger tires.



TJR
 
Same issue here... Seeing as my speedometer was about 2 mph off the other way, I just figure as long as I go the speed limit, Ill only actuall be going a little over.



Is that all that will be affected is the speedometer? Would there be any affect on the transmission, or anything else by not reprogramming for the larger tires?

 
same size tires as you mine read MPH lower also i recalibrate with my tuner from WFoy (Wayne) it is dead on the money against 2 different gps units
 
The only main issues are if the speedo reads faster then your going, you will put more miles on the odometer than are really on the truck, and if the speedo is off, the computer will adjust the tranny shift pints to the incorrect speeds, thus you may get weird shifting, lower or higher lock up points, different emissions controls.



I would recommend a call to a dealer and see if they would do it for you..

Or as stated above, get a flasher and have unlimited adjustments..

Todd Z
 
OK so let me get this staight, If my speedo reads 60 I will actually be doing 65 right so then my odometer will actually read less than the actual miles right???
 
Bigger tires means you travel a little further per revolution than your computer thinks so, yeah, your odometer and speedo read less than actual.



I went to three Ford Service Depts. before I found one able to reset my computer for larger tires, cost me around $120.00 total. Should have gone straight for the XCal.



I'd get it done somehow, though, big difference when shift points are restored to normal.
 
I can get it recalibrated for $35 at my local Ford dealership. I actually have an appointment to have it done in the morning. I just didn't know if it was a waste of money or how much difference it would make. Seems to drive ok and I haven't got a speeding ticket YET!!! Thanks for all the replies.
 
I talked to my dealer today and he said it would be $75 to do the adjustment. I went from a 255 75 r16 to a 285 45 r22. Would it be worth my money to go this route or a computer like xcal upgrade?
 
It is up to you.



We are going to put larger tires on our 2000 Explorer. (from 235/75-15 to 30 x 9.50-15) We are going to get an XCal tuner for it. Not only will it adjust your speedometer, but you will get better mileage, better power and driveability, and most of all, better shifts.



For me, the benefits of the tuner is worth the extra cost.



The question is if it is worth it to you?





Tom
 
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