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Discussion Starter · #1 ·
Hi All,

need your help , i have installed Mickey Thompson Tires ATZ PS3 size 315/70 R17 .. 35 tire size. i've programmed tire size 35 , but felt like the speedometer not giving me accurate speed . then i done the measurement it gave 33 and inches above , so reprogrammed the tire size to 33.85 still felling it is not accurate ..

Can anyone guide me and help me if he/she faced the same issue and what is a correct size should program it.

Thanks in Advance
 

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:crazy:Hers your math as I have understand it
315devide24.5=12.857X.70=9X2=18+17=35
As I have understood from another post here this math figures out height in inches from metric tire sizes
I did the math on my stock sport s tires than measured it worked out for stock sport s sizes hope this makes sense and helps ya
 

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NOT! find the revs per mile for the tire then divide into 63,360 inches/mile. Then divide result by 3.14 to determine tire diameter. That is the real height of the tire.
 

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for the sake of programming park on a flat cement surface at whatever psi you are going to run. Measure from center of hub to the ground and X2 and that is what you need to program for tire size. I have done it that way several times and so have friends and it always is spot on both speed and odometer when compared to stand alone gps'
 

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as you say it does not "feel" right.. get a GPS and verify the true speed... simple and easy.. can even download a gps app for your phone, then you will know how far your off..
 
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