Selecting the right scooter parts can often be a challenging process for a first time motorcycle owner. Of all the parts for a scooter repair or replacement, few are initially as confusing as determining the correct scooter tire size for your rims. However, once you learn the tire size ‘secret code’, you should have no trouble selecting the right tire for your street legal machine.
Most of the confusion is due to the simultaneous use of two different systems; the oldest inch pattern and the newest millimeter / inch hybrid system. A classic example of an inch tread scooter tire size is 3.50-10. These are still very common on old Italian scooters, their modern clones, and their knockoffs. Just read 3.50-10 as the inch measurement of the scooter rim; in this case, 3-1 / 2 inches by 10 inches. Other popular sizes of inch patterns are 3.00-10 and 3.5-8.
The newer millimeter / inch hybrid encoding is where it gets a little tricky. This will always be read as three sets of numbers separated by a slash (the millimeters) and a dash (the inches). A typical example is the common size 120 / 70-10. The numbers before the bar (in this case 120) indicate the width of the tire in millimeters when mounted and inflated. These two or three digits will range from about 80 to 160.
The two digits following the slash are called the aspect ratio, usually between 50 and 90, and are read as a percentage. Multiply the width (the number before the bar mark) by the aspect ratio number, and the result gives the height of the tire between the bead of the rim and the tread. For example, multiplying 120 x 70 shows that this tire has a height of 84 mm. The number following the dash represents the tire’s diameter measurement in inches.
So a 120 / 70-10 tire would be 120mm wide, 84mm from the tread to the rim, and 10 inches from the top to the bottom of the rim. Buying the best rubber parts for scooters becomes really easy when you learn to read the code.
Many of the early scooters of the 1950s and 1960s, and many of the retro-styled models today, sported the same size front and rear wheels. Typically 8-10 inch in diameter these were the classic ‘little wheels’ from the Golden Age of scooterdom. Sharing an attribute with their larger motorcycle siblings, many contemporary scooters require a wider or even larger diameter tire on the rear wheel than the front. This is usually the case with scooters with larger displacement engines; Yesterday’s 50 and 125cc engines simply didn’t require the same amount of rubber on the tarmac to ensure gyroscopic stability as today’s 250cc maxi-scooters.
Most of the major scooter tire manufacturers, such as Kenda and Michelin, have mounting charts on their websites. Make things as simple as possible for the scooter owner; You can simply search for the make and model of your scooter, and then see what rubber is made for it. Selecting the right rubber parts for scooter rims has never been easier.
