Tire speed gear ratio calculator

Just found this online calculator and thought I would pass it along. Works really great.

http://vexer.com/automotive-tools/speed-rpm-calculator

Has been posted in the tech archives here for years. Tech section has a bunch of good info gathered over time by the members.

Here's a good one for comparing tire and rims specs:

http://www.rimsntires.com/specspro.jsp

That one should be added to the tech archives also.

Thank you for the info. best thing I did was follow Kunkels' advice & measure rollout then divide Pi into it for the actual dia. before that I was placing a piece of flat stock on top of a rear tire & measuring from underneath it to ground with the tire at its psi it reaches when its been ran for awhile.