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I am in the process of scouting class VI roads for the association. One issue I have, for correct reporting, is that I need a new speedo gear. Which I am going to get in the near future, but today I went out and hit 4 roads.

How would I go about converting what my odometer says I traveled to what it really was?

I have stock gears in TC, 488s, on 33s (which measure 32s). What formula can I use to determine the correct mileage?


On a side note... In case you were wondering... I am running 488s on 33s because I'm going to 35/36s.

Thanks

FWIW reporting the length doesn't have to be exact....one thing you can do is some of the mapping websites if the road is on there

Scott Hatch wrote:FWIW reporting the length doesn't have to be exact....one thing you can do is some of the mapping websites if the road is on there

10-4 Thanks

First, the XJ odometer isn't always exact when stock. My XJ with 31's (no other change) is dead on according to GPS when it should read about 10% short of actual.

If you don't have GPS to check it against then just use highway markers (drive 10 miles on the highway by the markers and see what the odo says it was) to see how far off it really is.

For the calculation...you've increased tire size roughly 15% (32-28/28 ) which alone should make your odo read 15% fewer miles driven than actual. Then you've lowered your gear ratio 37% (4.88-3.55/3.55) which alone should make your odo read 37% higher miles driven than actual. So the difference of 22% should make your odo read that much higher than your actual miles driven.

get on the highway, drive past 5 mile markers and see what your odo says.


5/odomileage = your conversion factor.