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Re: gearing

To: jslz3@hotmail.com
Subject: Re: gearing
From: TeamZ3@aol.com
Date: Thu, 22 Apr 1999 11:57:51 EDT
In a message dated 4/21/99 9:57:55 PM Central Daylight Time, 
jslz3@hotmail.com writes:

> Q1
>  I'm currently running 24.8" Od R-1's on my car If i switch to a tire 
>  with a 25.7" Od  how much will my gearing change?

Divide the old diameter by the new diameter and multiply by the existing rear 
gear ratio to get the new equivalent ratio.  (24.8/25.7) x 3.45 = 3.32 
effective rear gear ratio

Divide the new tire OD by the old tir OD and multiply by the previous top 
speed to get the new top speed.  (25.7/24.8) x 62 mph = 64.2 mph new top 
speed in 2nd gear.

If this is for your Z3 I think you'll have problems with 25.7" OD tires.

M Sipe



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