Here, we’ll guide you through each step in determining motorcycle tire sizes, explained so that you can go ahead and hit the open road! There are five main aspects to determining the ideal motorcycle tire sizing: width, aspect ratio, speed rating, tire construction and rim diameter. Let’s take a look at each: Let me explain the sizes. The first Number which is 275 is the width of the tire, that's from edge to edge it's actually measured in millimetres but anyway it's the bit of the tire that actually has tread on it and touches the road shown in the image with a red arrow. The second number is 50, this is the width of the tire wall from the hole in Is the ratio of the height of the tire's cross-section to its width. The two-digit number after the slash mark in a tire size is the aspect ratio. For example, in a size P215/65 R15 tire, the 65 means that the height is equal to 65% of the tire's width. The bigger the aspect ratio, the bigger the tire's sidewall will be. Now, this information could read in a few different ways. For example, it could simply say 35x12.5 R17, or it may show as P265 75 R15. If it is the first listing, then here is the breakdown. That first number is your tire size at 35", and then the second number tells you the tire width at 12.5". That third reading is the tire type as radial and Metric tire sizes are a bit demanding when it comes to understanding what size they really are. Those numbers are only good with the other two. A 33 is a 33 no matter what, but a 265/70/16 is a 30 1/2" tall tire and a 265/75R17 is a 32 1/2" tall tire. The width of the tire is shown in mm (millimeters). In the example above, the number 195 can be seen. This means that the tire is 195 mm wide. The width of the tire can vary from 125 mm to 335 mm. The width always goes in steps of 10 mm. Tire sizes range from 125-135-145-155-165-175-185-195-205-215-225-235, etc. At some point on a tyre sidewall, usually on a lower edge, there will be a number comprising four digits. The first two numbers state the week of the year in which the tyre was made and the second two give the year. So ‘3620’ means the 36 th week of the year 2020. The age of a tyre matters, even if it is new. The first number in the code indicates the width of the tire in millimeters. This is the width as seen head-on. Our tire, in this instance, is 205mm wide. The second number in the code tells you the sidewall height, which is measured from the inner edge of the tire to its outer edge. This is represented as a percentage of the tire’s width as The first number is the easiest and measures the width of the tyre in metric millimetres. 235 means your tyre is 235mm wide. 235/ 45 R17. The second number refers to the profile of the tyre or the height of the tyre’s sidewall. The number isn’t in millimetres but is instead an aspect ratio measurement of how the height relates to total width. How to Read a Tire Size. It’s simple to understand what all of the letters and numbers on your tire’s sidewall mean with a little explanation. The numbers correspond to the tire’s size, width, and performance. For example, (235/35R18) Note: 235 refers to the width, 35R is profile, The 18 at the end is size. OXzOWzx.