Formula for Calculating Spedometer Accuracy
Formula-Calculating Speedometer Error
Original Tire Revs / New Tire X Indicated speed (speed you want calculated) = Actual speed
/ = divided by
Tire RPM can usually be found in tire specs.
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Example: Mk I Rabbit
175/70-13 22.6
185/60-13 21.7
215/50-13 21.6
155-13 890 rpm
215/60-13 957 rpm
890 / 957 = 0.929
0.929 X 55(mph) = 51.095
55mph is actually 51mph
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Original Tire Revs / New Tire X Indicated speed (speed you want calculated) = Actual speed
/ = divided by
Tire RPM can usually be found in tire specs.
________________________________________________________________________________
Example: Mk I Rabbit
quote:[HR][/HR]im putting 215/50/13 tires on my rabbit how will this affect my speedo and my odometer please any help is greatly appreciated[HR][/HR]
155-13 22.8" diameter175/70-13 22.6
185/60-13 21.7
215/50-13 21.6
155-13 890 rpm
215/60-13 957 rpm
890 / 957 = 0.929
0.929 X 55(mph) = 51.095
55mph is actually 51mph
