RE: Formula for tire size conversions

["Dan Cooke cooke@bng.ge.com" <COOKE@bng.ge.com>]

>
>I've been searching for a new technology tire in the 195 60 14 size but have 
>struck out.  Since I don't wish to pay for larger wheels for my 9 yr old 
>car, I'm investigating 195 55 14s and 205 55 14s.  Originally, the car came 
>with 185 60 14s.
>
>Can anyone supply me with the formula to calculate the wheel circumference 
>so that I can see the differences in the two tire sizes?
>
>Thanks for your consideration.  glenn
>
Specification  Sidewall  Radius  Diameter  Circumference  Revs/Mile  Difference
185/60-14         4.4in  11.4in    22.7in         71.4in        887        0.0%

195/60-14         4.6in  11.6in    23.2in         72.9in        869        2.1%
195/55-14         4.2in  11.2in    22.4in         70.5in        899       -1.3%
205/55-14         4.4in  11.4in    22.9in         71.9in        882        0.6%

Difference is compared to the first tire listed.

Dan.