----- Original Message -----
From "Keith Turk" <kturk at ala.net>
You really need to measure the tire on the car... wear being what it is and
all.... the ideal way to do it is to measure from the ground to the center
of the axle and then double that number... this takes into account the
amount of squat the tire has....
But we aren't even that fancy at Bonneville...
Keith, with deference to your expertise at Bonneville etc., I believe the
reason one needs the diameter of the tire is to solve for the circumference
of it -- i.e. the distance covered by one revolution of the wheel. The
circumference, for all practical purposes, won't change with tire squat --
only the portion of the circumference that lies flat on the road. For that
reason, I would think it would be more accurate to measure the diameter with
no load on the tire to get a true (to what extent possible) rolling
circumference. I dont know that there is an accurate way to measure tire
growth under high rpm, but that will also change the circumference and,
therefore the distance covered per revolution of the wheel.
Tell me where you think I'm wrong here, but this makes perfect sense to my
tiny, little brain.
79 MGB LE
"You only need two tools: WD-40 and Duct Tape. If it
doesn't move and should, use the WD-40. If it
shouldn't move and does, use the duct tape."