Question about Superchips Trail Dash 2

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lgarrett65

Member
I have the TD2 and I noticed that my Speedometer is off by 5mph. I do have the tire size set (which is 35") and my gear ratio set correctly (which is 3:73). So I can't figure out why I'm still off. Any suggestions greatly appreciated.
 
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Drdiesel1

New member
lgarrett65 said:
I have the TD2 and I noticed that my Speedometer is off by 5mph. I do have the tire size set (which is 35") and my gear ratio set correctly (which is 3:73). So I can't figure out why I'm still off. Any suggestions greatly appreciated.
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What is the tire size, on the sidewall of the tires ? Some so called 35's are actually 34's.
 
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lgarrett65

Member
You can only enter in .25 increments. So what I have read is you go up to the next .25, that would be 35. I could drop it to 34.75 and see what it would do, I guess.
 
Goldeneagle1LC

Goldeneagle1LC

Member
lgarrett65 said:
You can only enter in .25 increments. So what I have read is you go up to the next .25, that would be 35. I could drop it to 34.75 and see what it would do, I guess.
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Measure from the bottom of your tire to the middle of your wheel. Then double it. That will give you the actual rolling diameter of your tire at your given air pressure. A tire is roughly egg shaped because of the weight of the vehicle. That number will give the most accurate speedometer read out.
 
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dldrace@gmail.com

New member
Goldeneagle1LC said:
Measure from the bottom of your tire to the middle of your wheel. Then double it. That will give you the actual rolling diameter of your tire at your given air pressure. A tire is roughly egg shaped because of the weight of the vehicle. That number will give the most accurate speedometer read out.
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Revs/mile give you the best indication of tire diameter - example BFG KM2 35's are 598 revs/mile working the math backwards comes out approx 33.75. I have a TD2 - in your case I would keep changing the tire diameter until the speedo and tach read correctly -I would guess around 34.00 or 33.75
 
Goldeneagle1LC

Goldeneagle1LC

Member
dldrace@gmail.com said:
Revs/mile give you the best indication of tire diameter - example BFG KM2 35's are 598 revs/mile working the math backwards comes out approx 33.75. I have a TD2 - in your case I would keep changing the tire diameter until the speedo and tach read correctly -I would guess around 34.00 or 33.75
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If you measure it you will not have to keep adjusting to figure it out. It will be right.
 
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