At 09:14 PM 10/14/2011, mark drillock wrote...
>Yes, we have been over all this before. That simple arithmetic gives
>one
>value while the real world tires are something else. That program
>gives
>rev/mile results way different than every tire company specification I
>have checked.

It is simply being misused. The Miata site calculator is intended to
compare different tire sizes, not give correct absolute results, and is
pretty accurate for that.

Tire size can't be used to directly calculate revs per mile - as soon
as you put a load on a tire, it flattens on the bottom. That reduces
the rolling radius, and it will do more revs per mile. That's why the
calculation underestimates.