Date:         Fri, 09 Feb 96 09:20:20 CST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         Joel Walker <JWALKER@ua1vm.ua.edu>
Subject:      Re: Tire Circumference (was: Engine  RPM (Re: Squeaky brakes))

On Fri, 9 Feb 1996 09:14:41 -0600 Michael A. Radtke said:
>So, having said all that, it would be best to measure the diameter of the
>tire horizontally to calculate the circumference.  For best accuracy,
>perhaps it would be best to jack the tire off the ground and measure the
>circumference directly.  Or, how about marking the tire and measuring the
>distance to roll the bus one revolution of the tire?

the "best" way to measure the circumference of a wheel, so i was told, is
to make a mark on the tire (masking tape works well), and a mark on the
ground (masking tape again) ... say, in a large flat parking lot (like a
way-back corner of the mall). it helps if you align the car along some
pre-painted line (like the parking space dividers). mark the ground and
the tire together, that is, align the two marks.

then roll the car forward, counting the times the tire mark makes a complete
revolution, until you've gone TEN revolutions of the tire. mark the ground
at this point, then measure between the two ground marks, and divide by
ten. this gives a very good figure, averaging in/out the inaccuracies of
crude measurements. :)

joel