Choosing the wrong tire can lead to tire failure or worse…Replacing your tires just requires to copy down the numbering of your current tires. Problems may arise, and it happens more often that you can think, when upgrading to a new brand or size. First things to do is to match your tires to the speed and load ratings. For example, no racing tires on a cruiser and tires adapted to the weight of your motorcycle. There are 4 main motorcycle tire designations (cruising, sport, off-road and racing) For each designation, you need to understand and how to convert 3 different measuring systems used by tire manufacturers, inch/metric/alphanumeric..
The Inch Measuring System. Used for stock and very basic tire sizes, the inch system of motorcycle tire numbering does not see common use. The Metric Measuring System. The most common of the tire size designations, known as the metric measurement, begins with the section width. The inch system is akin to the car tire measurement system..The Alphanumeric Measurement System. Invented by the British and largely phased out by metric tire numbers. Alphanumeric codes are uncommon on today’s tires.
Below, I published tables giving the tire size, speed and load rating conversions across all 3 numbering systems.