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Old 12-16-2010, 02:03 PM
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new speedo gear needed for 31's?

I have an '06 TJ and went from the wampoo stock tires to 31x10.5x15. It is recommended to change out speedo gear to get accuracte mph as well as mpg figures? MPH doesn't seem too far off but miles driven on amount of gas seems way off.

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Old 12-16-2010, 02:09 PM   #2
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I would run with your GPS first. I have an 04 Sahara, and when I upgraded from the stock 30's to 31's my speedo read more accurate than before. Now it's possible that the PO had already upped to 31's and changed out the speedo gear and then the dealer I bought it from put on new stock size tires. But the GPS will be the quickest easiest way to tell if you need to change speedo gear.

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Old 12-16-2010, 03:17 PM   #3
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Usually with a 1" gain in tire diameter, it's not nessessarey to change speedo gears. However, a 3" gain in tire diameter requires one.

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Old 12-16-2010, 03:58 PM   #4
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So 31s don't really need new gear?
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Old 12-16-2010, 04:34 PM   #5
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Man....those HUGE 31's are going to screw everything up!!!
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Old 12-16-2010, 04:53 PM   #6
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Really crap what should I do
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Old 12-16-2010, 04:55 PM   #7
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THis is my first wrangler
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Old 12-16-2010, 06:30 PM   #8
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^^ haha I think he was kidding. internet sarcasm is quite tricky to pick up. I think you'll be fine w/o regearing/adjusting your speedo.
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Old 12-16-2010, 07:27 PM   #9
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Do the gps thing... did you change wheels too, by any chance? Heavier tires and wheels will affect mpgs quite a bit.....

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