Calculating speed, diff ratio, tire size etc.

["Chris R Harris" <yesford@clear.net.nz>]

Greetings Team, knew I had this formula somewhere, hope its of help to some
members.

              RPM x Tire Dia
MPH =    -----------------------
              Diff Ratio x 336 


              MPH x Diff Ratio x 336
RPM =    ---------------------------------
                       Tire Dia


                  RPM x Tire Dia
Diff Ratio =  ----------------------
                   MPH x 336

Out on the salt it pays to subtrack 5% on the MPH calculation.
A better formula is one that uses the 'Loaded Wheel Radius' with a
different constant, instead of Tire Dia and 336, but have unfortunately
lost it.

All the best for WOS people, I wont be back till Speedweek 2001 so don't go
kicking those records over the moon !

Chris Harris  C/GR  # 397.   New Zealand.