I found this Axle Ratio/Tire Size Calculator - Version 1.0 out on the web. This will Help with all those conversions

Here are a few calculators that may be useful in deciding tire size and gear ratios (and other useful? info). These should be compatible with Netscape 3.x and MS Internet Explorer 3.x or above. If you find that they are not, send an E-mail with a description of the problem and the version/make of the browser being used.

Doesn't work?
Jump over to the Gear Table
for the same information in printable form.

Now that you have your truck lifted, you want bigger meats. They look cool and have the potential of being very functional, but they may also be robbing you of power/gas mileage. This calculator will get you back to a ratio that's closer to your original. Enter the values on the left and press Compute.

Ever wonder what your low-low-low gear ratio is, your "crawl ratio"? You'll need to do a little research by finding out the transfer case and transmission ratios first. Enter your values on the left side, press Compute and your answer will be on the right.

I've spend a bunch of time trying to WAG (wild ass guess) my actual MPH when going down the road. By knowing your gear ratios and tire size you'll get a more accurate idea here. Enter the value on the left, press Compute.

I suppose if you don't have a tachometer you could use this form, otherwise it's only useful to find out how accurate your Tach is. Enter the values on the left, press Compute.

Send me your formulas for "useful" calculators and I'll include them.

--Mark Medina