Bigger rear diameter tires will help some, more than you would think.

See this chart: http://www.sierrabronco.com/TireGearRatio.htm


I suggest jacking up the rear of your truck and figuring out just what gear ratio you have:

Pulling the rear differential cover (& counting the teeth) is the most accurate method to determine gear ratio but another way to check the rear end ratio is to jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posis and lockers -or- 2 full revolutions for open diffs. Carefully count the number of full revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 ¾ turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading.

Once you know what you have you can make an educated decision on what to do!

I hope this helps!



Last edited by Hot Rod John; 10/15/2010 12:43 AM.
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