At 02:26 PM 3/16/2010, John Bange wrote...
> > I am wanting to know what the revs per mile of the Michelin
> Agilles >205/65R15 C is
>I use this calculator:
>
>http://www.miata.net/garage/tirecalc.html

That calculator is way off with regard to rev/mile. It might be useful
in comparing two different sizes, but not actual tires, since the only
measurement of a real tire which can be expected to be exact is rim
diameter. A tire with a section width of 210 may be called a 215,
because 210 isn't a standard size.

The problem with that calculator, and others I've seen, is that it
figures diameter mathematically, assuming perfect circles, etc. A real
world tire has a rolling radius which is smaller than that of a tire
represented as a perfect circle (it compresses when loaded), which
means it will turn faster.

So where that calculator says a 215/60R16 does 771 revs/mile, Falken
says their ZE-912 of the same size does 808. That's about a 5%
difference.