speedo changes

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speedo changes

Postby Skeletor » Fri May 05, 2017 11:15 am

has anyone noticed a change in their speedo....when they installed much larger tires in their first gen Trooper ?

if so, how much ??
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Re: speedo changes

Postby JoeIsuzu » Fri May 05, 2017 12:53 pm

Skeletor wrote:has anyone noticed a change in their speedo....when they installed much larger tires in their first gen Trooper ?

if so, how much ??

You won't see any change in MPH (as indicated on the speedometer) vs RPM. It will change your ACTUAL speed.

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Re: speedo changes

Postby oldestisuzuist » Fri May 05, 2017 6:47 pm

With larger tires the speed & odometer readings at a given rpm will decrease 3%-4% for each 1" difference in tire diameter within the range of tire diameters that one would normally use. The smaller the tire diameter the greater change percentage per 1" change. At the same time the actual travel speed will increase by the same amount.
A typical new tire has around 16/32" tread depth, so the as the tire wears from new to bald the same variance gradually occurs because the tire diameter decreases about 1".
The speedo reading can be changed by changing the driven gear on the end of the speedo cable to a different tooth count, one tooth difference typically changes the reading by about 5%-6.6%. The smaller the tooth count the greater the change per tooth, fewer teeth increases the speed/odometer readings. Tooth counts range from 15 to 20 that I know of.
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Re: speedo changes

Postby JoeIsuzu » Fri May 05, 2017 11:17 pm

We're saying exactly he same thing, but a different way.

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