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Discussion Starter · #1 ·
Does anyone have a directional idea of what the speedo correction factor is if you running 33" tires??
 

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Nice to see the gears drop down to a reasonable price again.
 

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Also, if you don't install the new speedo gear and you have the stock speedo gear, you can manually calculate it by figuring out the circum. % difference between the stock tire (printed on the door VIN label) and the 33" tire.

So if the 33 inch tire happens to have a 15% larger circum. than stock...then when you calculate MPG (miles/gallon), you want to add that 15% back in to get a "better" (not perfect) calculation.
 

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Also, if you don't install the new speedo gear and you have the stock speedo gear, you can manually calculate it by figuring out the circum. % difference between the stock tire (printed on the door VIN label) and the 33" tire.

So if the 33 inch tire happens to have a 15% larger circum. than stock...then when you calculate MPG (miles/gallon), you want to add that 15% back in to get a "better" (not perfect) calculation.
What is on the door is usually the very base model size and not the size it may have been optioned with.
 

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I run 33X12.5X15 and compared to GPS speed I'm only showing 2-3 mph slow on the speedo. Its not worth changing.
2-3 MPH off... not that bad I agree...

but for around $20.... it can be corrected with the proper gear. When I regeared for my 33's to 4.56's... my speedo was off a good 15 mph or better.
 

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Changing the gear takes all of 5 minutes. Its super easy. Follow the directions on the link by Unlimited. Ive got mine in a box waiting to go on the jeep next week. It sits in the garage with the tires and wheels and ZJ springs. I need to get on the ball and straighten up my garage. LOL
 

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Changing the gear takes all of 5 minutes. Its super easy. Follow the directions on the link by Unlimited. Ive got mine in a box waiting to go on the jeep next week. It sits in the garage with the tires and wheels and ZJ springs. I need to get on the ball and straighten up my garage. LOL
Just exercise care on the re-seating the gear and keeping the O-ring intact.
 

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Discussion Starter · #11 ·
2 to 3 MPH at 15 MPH maybe. I'm 16% off that's a big difference at 65 MPH. I've calculated with GPS. I have 33's also.
Did the GPS test today .....
@ 30 doing 31
@ 40 doing 42
@ 50 doing 53
@ 60 doing 63
@ 70 doing 74 ..... you get the idea

not as much difference as I expected considering the tires sound like I'm doing 110 all the time :whistling:
 

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Mine is almost 10% off all the time.. however, my tires are pretty quiet and seem to work pretty good offroad too.
Dana
 

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Yes. Odometer miles will be off too due to the longer rollout of the bigger tire.
 

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Johnrmclean said:
Did the GPS test today .....
@ 30 doing 31
@ 40 doing 42
@ 50 doing 53
@ 60 doing 63
@ 70 doing 74 ..... you get the idea

not as much difference as I expected considering the tires sound like I'm doing 110 all the time :whistling:
Just out of curiosity, what tires are u running ? I know you said 33s
 

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Discussion Starter · #17 ·
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