Understanding
Tyre Side Wall Markings

• 1. Width

  This number indicates the tyres section nominal width measured in millimetres from sidewall to sidewall, so in this example a '190' tyre is 190mm.

• 2. Aspect Ratio

  This number indicates the tyres aspect ratio or height expressed as a percentage of its width. In this example the aspect ratio is '55', so 55% of 190mm width makes the height 104.5mm.

• 3. Construction & Speed Rating

  In this example it states 'ZR'. These two letters represent two different meanings, the 'Z' is the tyres speed rating so in this example, the tyre is rated for speeds in excess of 168mph. The 'R' means that the tyre is a radial construction. If the 'R' is omitted, then it means the tyre will be a bias/x-ply construction. 'ZR' is often seen on most modern sports/touring radial tyres.

• 4. Diameter

  This number is the bead seat diameter of the wheel in inches so in this example, 17 inches.

• 5. Usage

  In this example 'M/C', this simply means the tyre is designed to be used only on motorcycles.

• 6. Construction & Tube Usage

  In this example 'Radial | Tubeless'. The Radial part of this section is again referring to the construction of the tyre. Most modern tyres will be a radial construction. The 'Tubeless' or 'TL' marking denotes that the tyre is a tubeless type tyre i.e. to be used without an inner tube. A 'Tubed' or 'TT' marking denotes that the tyre is a tubed tyre i.e. the tyre is supposed to be used with an inner tube.

• 7. Load & Speed Index

  In this example, '75W'. The '75' is the load index (see table below for a full list). This indicates a maximum load of 387kg per tyre is permitted. The 'W' element is the speed index (see table below for a full list). This gets a little confusing given the 'ZR' information mentioned above (although not all tyres are 'ZR' tyres). The significance to the load and speed index numbers being together is it indicates the maximum speed at which the tyre can carry a corresponding load so in this example, this tyre is suitable to for speeds up to 168mph with a maximum weight of 387kg.

• 8. Direction

  This is self-explanatory, but the arrow indicates the direction of rotation according to the fitting position on the motorcycle.

• 9. DOT Certification

  The 'DOT' marking stands for U.S Department of Transportation. It indicates that the tyre conforms to the regulations issued by the transport departments of the USA and Canada.

• 10. Production Date

  One of the most useful bits of information on a tyre sidewall but very few people know it's there! Usually stamped just after the 'DOT' marking is a series of four numbers. This denotes the production date of the tyre with the first two numbers identifying the week and the second two numbers identifying the year. So in this example, '0420' means the tyre was manufactured during the 4th week of the year 2020.

Motorcycle Tyre Load Index Table: