Speedometer is off
#1
JK Newbie
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Join Date: Feb 2014
Location: New York, NY
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#2
JK Freak
The inputed tire size is larger then what you actually have. Don't rely what is printed on the sidewall.
Use a tape measure and re-measure your tires. Generally I find that they're smaller then listed.
Use this information to re-calibrate your computer
Use a tape measure and re-measure your tires. Generally I find that they're smaller then listed.
Use this information to re-calibrate your computer
#3
JK Jedi Master
What Rod wrote above. I've found the quick way to do it is to measure from the ground to the top of the tire shoulder where it makes a sharp break into the tire tread. Typically that's an inch or more smaller than the expected tire size. The accurate way to measure is to mark a spot on the ground and on the tire where it contacts the ground. Then drive forward until the tire mark reaches the ground after one revolution. Measure from the tire mark back to the first mark (on the ground). Divide by Pi. That is your actual tire size. Just for reference, my "35 inch" Duratracs read accurately on the speedometer when the ProCal is set to 33.25".
#4
#5
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What Rod wrote above. I've found the quick way to do it is to measure from the ground to the top of the tire shoulder where it makes a sharp break into the tire tread. Typically that's an inch or more smaller than the expected tire size. The accurate way to measure is to mark a spot on the ground and on the tire where it contacts the ground. Then drive forward until the tire mark reaches the ground after one revolution. Measure from the tire mark back to the first mark (on the ground). Divide by Pi. That is your actual tire size. Just for reference, my "35 inch" Duratracs read accurately on the speedometer when the ProCal is set to 33.25".