For racing tire sizes, try this formula: nominal diameter times tread width times bead diameter. Example: A 32.0 x 14.0 x 15 is a 32-inch tall, 10-inch-wide slick that goes on a 15-inch diameter 55 refers to the profile of the tyre, or the distance between the wheel and the edge of the tyre, looking at it from the side. The number is the percentage of the width of the tyre. It is commonly known as the “aspect ratio”. So, the profile of our example tyre is 55% of 205mm, or 112.75mm. This number also increases in increments of 5. How to read metric sizes: P255/60R17 102V Tire Class : P Tire tire class of this tire size is 'P' which means it is a passenger car tire. The first letter in the Section Width : 255 The width of this tire size is 255mm wide. The first number in a metric tire size is the section Aspect Ratio : Check the ISO sizing, if available. If you read your bike tire sidewall, there’s a combination of numbers that have 5 digits in total – 2 at the front and 3 at the end, separated by a dash in between. That’s the ISO sizing, which stands for International Standardization Organization – a more accurate way to measure your bike. 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. The R means radial, as in the construction style, while the 16 means it rides on wheels with 16-inch diameters. 1. Metric, or tire type. 2. Tire width. 3. Rim diameter. 4. Speed rating. ONGjWF. The first of the two numbers is the nominal section width of the tyre. It is given in millimetres and defines the distance between the inner and outer sidewall of the tyre. For example, 205 means that your tyre is nominally 205 mm wide. The second number is the relationship between a tyre’s sidewall height and the tyre's width. Watch on. In essence, your car’s wheel and rim size can be read as: [rim diameter (inches)] x [wheel width (inches)] [bolt pattern and spacing (millimetres)] [+/- wheel offset (millimetres)] Note, however, that with some wheels, the measurements between the bolt pattern/spacing and the offset can interchange positions. How to Read a Tractor Tire Size . Locate your tire size on the sidewall of the tire (see picture above). The first number(16.9) represents the tire width sidewall to sidewall in inches. The second number(30) represents the rim diameter in inches. How to Read a Metric Tractor Tire Size . Metric Size Conversion Example: Tire Size – 280/85R24 265 = Section Width in millimeters (measured at the widest part of the tire from sidewall to sidewall) /60 = Aspect Ratio or section height to width ratio as a percentage. For this example, the side wall is 60% of the section width of the tire (265mm x .60 = 159mm). Therefore, the sidewall height is 159mm. 18 = This is simply your rim diameter 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.

how to read tyre dimensions