Tires come with different markings and it can be difficult to understand which ones to choose for your scooter. Furthermore measures may be quoted in inches or millimeters. Use common sense to understand which metric is being used. (1 inch = 25.4mm)

e.g. 10x2.25 or 10x2.5 or 10x3.0:
This type of sizing is common for electric scooters. It is quoted in inches. The first number refers to the diameer of the tire. The second is the tire width. The sidewall is typically the same as the width. So if you deduct the the sidewall x 2 from the tire diameter you get the approx. diameter of the rim. This is not an exact science as we know that all of these sizes will fit on a 6 inch rim.

e.g. 80 / 65 - 6
This type of sizing is more common for motorcycles. 80 refers to the tire width when mounted and inflated. It is quoted in mm (80mm = 3.15 in). The second number 65 refers to he aspect ratio in %. It is the height of the sidewall expressed as % of the tire width. In this case it is 65% x 80mm = 52mm. The last figure is the rim diameter in inches. Many retailers will sell this tire as a 10x3. While they are usually interchangeable, the 10x3 looks a little slimmer than the 80/65-6.

Note that actual tire sizes may vary across manuafcturers, even when they come with the same size denomination. You will want to make sure that your place of purchase has ensured they fit your scooter.