TIRE TECH PAGE
Since nobody else will explain tire sizing to you, here it is.....
First number (195 or 205) is the overall width of the tire, not the tread width.
Second number (65 or 60) is the aspect ratio. The sidewall is 60% (or 65% or...) as tall as the tire is wide.
Third number is wheel size.
As a tire gets a lower aspect ratio, the tread gets wider, so a 195/60 will have a wider tread than a 195/70.
Figure out tire diameter as follows:
width * (aspect ratio * 2) / 2540 + wheel size
A 205/60/14 is only about 1% shorter than a 195/65/14 but will have a wider tread width.
HERE ARE SOME HELPFUL LINKS TO LEARN MORE ABOUT TIRE TECH THAT MAY HELP YOU IN YOUR RACING. Traction ratings, speed ratings, tread wear and more are explained on some of these links as well as some helpful conversion charts.
http://www.miata.net/garage/tirecalc.html -comparison chart for rpms
http://www.dakota-truck.net/TIRECALC/tirecalc.html -tire size calculator
http://www.dsm.org/tools/tiresize.htm -tire size calculator
http://www.tirerack.com/tires/tiretech/general/utqg.jsp -ire tech
http://www.us23.com/tires/html/tire_info.html -tire terms
http://www.car-videos.com/tools/speedrpm.asp -speed/rpm calculator
http://www.onlineconversion.com/
-metric to standard conversion chart