Speedometer Readings With "Shorter" Tires

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Mar 25, 2006 | 11:23 PM

rikhek

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Safety Car

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From: Tulsa Oklahoma

Speedometer Readings With "Shorter" Tires

Will I see a "false" speedometer reading going from a "taller" diameter tire on the rear to a "shorter" diameter tire? High or low if any? My current rears are 0.5" less diameter than what I previously had.

Rick

Mar 25, 2006 | 11:27 PM

Stangkiller

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From: Houston, Tx Got traction?

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St. Jude Donor '07-'08

yes your speedomitor is dependent on Tire size, if you change your size you will change your speedo reading.

Mar 25, 2006 | 11:29 PM

rikhek

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From: Tulsa Oklahoma

Yeah..... that was my question. Will it read a faster or lower with the shorter tire?

Mar 25, 2006 | 11:33 PM

Warp Factor

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From: Metro Detroit Michigan

Quote:

Originally Posted by rikhek

Yeah..... that was my question. Will it read a faster or lower with the shorter tire?

Faster. More tire revolutions per mile.

Mar 25, 2006 | 11:35 PM

Stangkiller

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From: Houston, Tx Got traction?

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St. Jude Donor '07-'08

Quote:

Originally Posted by Warp Factor

Faster.

A smaller tire means the tire will spin more to travel the same distance. A larger tire means the tire will spin less to travel the same distance. Therefore a shorter tire will cause your speedomitor to read Higher than your actual speed, while a taller tire will cause your speedomitor to read lower than your actual speed. Please not this also affects the rate at which your odometer gets its milage from as well.

Chris

Mar 26, 2006 | 12:26 AM

rikhek

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From: Tulsa Oklahoma

Thanks guys.

Rick

Mar 26, 2006 | 01:55 PM

MagikDraggin

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Quote:

Originally Posted by Stangkiller

Chris

Can this difference be compensated for through computer reprogramming?

Mar 26, 2006 | 04:51 PM

SpeedyD

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From: Watertown CT

I threw some numbers together here, and I came up with, if you decrease your tire diameter by 1/2 inch, when your car is reading just over 71, it worked out to be 71.32mph, you're actually going 70mph. It works out to if you actaually travel 10,000 miles, your odemeter will have said you traveled 10,188.67 Someone can correct me if I'm wrong, which I very well might be, but that's what I came up with. Good Luck Dan