Stock Gear Ratio

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Oct 30, 2007 | 11:53 AM

Stl94LT1

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Joined: Apr 2006

Posts: 1,083

From: O'Fallon, MO

Stock Gear Ratio

My GF bought new tires/wheels for her 95 A4 TA. I need to know the stock gar ratio to recalibrate the speedo. Is it 3.23:1?

Oct 30, 2007 | 11:59 AM

Injuneer

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Joined: Nov 1998

Posts: 71,098

From: Hell was full so they sent me to NJ

The PCM has two seperate entries.... one for the tire size and one for the rear axle ratio. You only have to change the entry for the tire diameter, and only if the outside diameter of the new tire is different than the outside diameter of the tire the PCM was programmed for. Affected only by the tire diameter, has nothing to do with the wheel diameter.

A4's had either a 2.73:1 (GU2) or a 3.23:1 (GU5) rear axle ratio, and you can look for the RPO code on the build tag.