i am gonna put bigger tires on my old truck and i need to know the formula to make the speedo think they are the same. you know bye lowering rear end ratio.

now: 28 inch tires and 3.08 rear end

soon: 31 inch tires and _________?

does somebody know the formula?
thank you so much

 

Check out http://www.bncoffroad.com/tire_gear_cal.html - it will calculate for you. If you really want the formulas, let me know.

In your case 3.08*31/28 = 3.41 (or 3.30 0r 3.55, since that those are the closest available ratios.

Ian

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

[This message has been edited by Ian N (edited 05-03-2001).]