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Will my speedo be off if i upgrade to 17's

S

stalkersvt

CEG'er
Joined
Jun 29, 2004
Messages
52
Will my speedo be off if i upgrade to 17's? will be 215/45/17, currenly run the stock se 15' wheels and tires.
 
All depends on your outer diameter. If you go up in wheel size, but down in profile an equal amount, you'll have no change.

For example, let's assume you were sporting a 205/65-15 setup.

Your profile, in millimeters, works out to 133.25 (205 x .065). Converted to inches (133.25 x 0.03937), that's about 5.25. Multiply by 2, and add that to the 15" wheel, and you've got a diameter of 25.50. So, that's the baseline in this example.

For practical purposes, you could also just use a tape measure with a properly inflated, unloaded tire.

Using the above calculations, your 215/45-17 setup is pretty close to the above example -- 24.61 inches. The effect on the speedo in this case will be small, but it will read slighly fast.
 
Last edited:
Necronommicon said:
If you are really worried about getting it so that your speedo is as close as possible then you need to check out this link, just input the tire sizes and a speed and it will tell you the difference if any. http://www.paspeedo.com/calculator.htm
Click to expand...

Or better yet, check the tire sizes from tire rack since even different brand tires with the same size, do have different specs and different diameters. The 235/19/19 I have in Goodyear Eagle F1s are 25.5". Originally I had bought some T/A Scorchers in the same size and they were about .5" taller. Best to check with tirerack since we want the ACTUAL size...not the theoretical in the above link. ;)
 
Thank you!

Thank you!

Thank you all, cant wait to get me some new shoes on the pimptour.
 
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