Tire Size Calculator (For actual car tires, not R/C)
Congratulations for finding this page, which really does not belong here. I put this here for my own use, but go ahead and use it if you want - after all, you're here now...
This calculator is based on a Java version I found somewhere on the net. But, I wanted to port it to javascript to make it easier to change, and so here it is. Anyway, you can use this to figure out what size tires you need if you get different rims. For instance, my car came stock with 205/50R17 tires, but wanted larger rims (18") and wider tires. But since I wanted to maintain speedometer and odometer accuracy, I had to make sure the overall diameter is the same.