I know that there are some programers out there that can change the speedo to your tire size anyone know what that programer is or a brand that does that?

 

Check out http://www.autotransinc.com/recal.htm - there was also a post last week on one of the boards about a competing product.

Also, if you have a 97 or 98, you can just change the gear on the Vehicle Speed Sensor (VSS).

Ian

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99 Expedition EB
5.4l, 4x4, 4.10 LS
WMS Tube, Bassani Cat Back Exhaust, Superchip Flipchip

 

I'm going from 255/70R-16 to 285/75R-16
I've got a 97 f-150 ext cab 4x4 5.4, auto w/overdrive 3.55 gears. Is that enough info for my less then helpful friends at the local Ford dealers parts counter? I fear the worst as I have played the speedo gear game with those boys before............

 

Take the gear off, count the number of teeth and then multiply that number by 30.1/32.8 (the old and new tire sizes in inches). So, if you have 19 teeth now:

19*(30.1/32.8) = 17.4 - so you could go to 17 teeth (speedo would read a bit high) or 18 teeth (a bit low).

The best approach is to go in and say "I have a 19 tooth and need a 17 tooth gear", that way they can't screw it up. You might want to call a speedo shop - they usually stock those gears and probably have a better selection.

Ian

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99 Expedition EB
5.4l, 4x4, 4.10 LS
WMS Tube, Bassani Cat Back Exhaust, Superchip Flipchip