Tire Diameter

[steve d ferguson]

I keep wondering
if my current wheel and tire combination is really smaller than the OEM
configuration, and if not properly taken into account, will cause the
height
adjustments (and consequently front end geometry) to be distorted when
forced to match the original height adjustment specs.

I don't see how front to rear height bias can be effected if you have
the same size tire on the front as the rear. Perhaps you need to have
your ride Height SET properly using the measurements in the repair
manual.
I went through everything on the front of my GMC to eliminate all of
the sway and the real clincher-thing-that-did it all was when the splined
coupler was replaced. I think now I could drive off of a curb and barely
feel it. BTW, prior to that I replaced all the ball joints, steering
link, bushings, added a 4 bag rear system, Bilsteins, rebuilt steering
box, 4-wheel alignment ,Caspro sway bar and ride height adjustment. It's
a real 1-thumber now on any kind of a road.
Steve
________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk! For your FREE software, visit:
http://dl.www.juno.com/get/tagj.

 

[roger umber]

Steve,
I found the following neat site that calculates the effect of different
size tires and rims on speedometer readings. It does not calculate the
effect of drive ratio changes.

http://www.miata.net/garage/tirecalc.html

Roger Umber
'78 SB Birchaven

Date: Tue, 18 Jul 2000 14:13:43 -0700
From: Steve D Ferguson
Subject: GMC: Tire Diameter

I keep wondering
if my current wheel and tire combination is really smaller than the OEM
configuration, and if not properly taken into account, will cause the
height
adjustments (and consequently front end geometry) to be distorted when
forced to match the original height adjustment specs.

 

[emerystora]

>Steve,
>I found the following neat site that calculates the effect of different
>size tires and rims on speedometer readings. It does not calculate the
>effect of drive ratio changes.
>
>http://www.miata.net/garage/tirecalc.html
>
>Roger Umber
>'78 SB Birchaven

Drive ratio changes are easy to calculate since it's directly
proportional to the ratios.

For example, if you change from a 3.07 to a 3.42 your speedometer
would change by 3.42/3.07 = 1.114.

So instead of showing 60 mph it would show 60 x 1.114 = 66.84 mph.

Emery Stora
77 Kingsley
Santa Fe, NM