How do I calculate the revolutions per mile of my tyres?
To obtain the true figure you should take the deflection into account and start with the diameter (in inches) less tread height. Therefore the calculation should be; tyre diameter (less 2x tread depth), multiplied by 3.142 to get the circumference, you should then divide 63360 (which is the number of inches per mile) by the circumference to obtain the revolutions per mile.
