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Speedo error correction

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Strahan, Dec 27, 2001.

  1. Strahan

    Strahan 1/2 ton status

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    Hey all. I was just using a tire size calculator to check my speedo error % when I cut over to new tires. I'm not sure how to convert 35 x 12.5 to the xxx/xxR15 format so I had to guess based on the calculator's diameter output and my memory on metic conversion (1 in = 2.54cm?) and came out to 325/80R15 or 315/80R15. If that's true, then there is roughly 20-22% speedo error. How does one correct that? If it were 20-22% too fast that'd be fine, keep me outta trouble hehe, but according to the tire calculator it's too slow. (http://www.miata.net/garage/tirecalc.html)
     
  2. txbartman

    txbartman 1/2 ton status

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    I have always used this My Jimmy with all her projects!
     
  3. Thunder

    Thunder 3/4 ton status

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    Here's a bunch of handy dandy calculators<a target="_blank" href=http://www.intercotire.com/html/calculators.htm>Tire size/gear/mph calculators</a>
    They should help you out.
    To get your speedo correct after putting on the bigger tires you need to change the speedo gear in the xfer case where the spedo cable attaches.

    <a target="_blank" href=http://coloradok5.com/gallery/Thunders-Blaze> Blazer pics</a>
     
  4. Strahan

    Strahan 1/2 ton status

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    Thanks guys. I'm glad I don't have a modern truck, hehe, just changing a gear sounds good to me :)
     

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