Our motorcycle tires are super important. Not only relevant to our safety but also to our motorcycle’s handling. By design, it’s easy to imagine they come with specific compounds design and of course approved safety/characteristic ratings or markings. These are noted on the motorcycle tire sidewall and help riders identify, buy and correctly maintain tires. Reading your motorcycle tire sidewall codes initially came about to identify the tire’s maker. But through the years, government legislation demanded safety markings be posted to help buyers know they are getting a legally approved tire.
Buying and using the right tire for your specific motorcycle or scooter is very important to its load, speed and overall performance.
The size of the tire needed for your motorcycle (if buying new from a dealership) comes already with the manufacturer’s preferred make/model and profile mounted on the bike.
Further, your owner’s manual provides the specifics you need when it comes to replacing your tires or if you wish to buy a special compound for the track or your long distance tour, etc.
Motorcycle Tire Sidewall Markings Fall Into Two Groups:
- Essential markings which tire manufacturers have always used to indicate: make, size and type (including maximum inflation pressure; direction of rotation).
- Additional markings these have been added over the years per requirements of legislation in the principal regions/country of use.
The markings and ‘code’ is noted on the side wall of both your tires tell quite some information which will differ from country to country. It can be confusing! This code has grown in complexity over the years and you’ll see this as it often combines a mix of metric and imperial measurements. They may also be ad-hoc extensions to lettering and numbering schemes. Each country or group of nations has its own regulating body. Most tires sold in United States or Europe will have a DOT / Department of Transportation date code.
In Europe, the European Tyre and Rim Technical Organisation (ETRTO) and the Tire and Rim Association (TRA) are two organisations which influence national tire standards and aim to align national tire and rim standards in Europe. An example would be “E2” – the “E” indicates that the tire conforms to ETRTO standard R75 and the “2” means that the tire was approved for this regulation by the nation of France.
In the United States, the Office of Vehicle Safety Compliance (OVSC), a component of the DOT (Department of Transportation) is one of the agencies tasked to enforce the Federal Motor Vehicle Safety Standard (FMVSS).
Canada has published tire regulations, such as the Motor Vehicle Tire Safety Regulations SOR 95-148. Other areas of the world may vary, so please seek out the proper information from your nation’s DOT.
Motorcycle Tires Have Their Own Set of Codes
As you might imagine, tires for motorcycles have their own set of codes different from automobile tires. The codes describe:
- Height/width aspect ratio
- Wheel diameter
- Load index and speed rating – Load index is the weight the tyre is capable of handling when properly inflated. Most tire manufacturers show on the sidewall what that maximum load is so there is no guessing you’ll usually find it listed with the tire’s maximum air pressure.
The most common codes/ratings you’ll see are shown in this example below. this is what you’ll see on a mid-size sport-bike front tire.
So let’s now decipher the following example:
Front Tyre: 120/70 ZR 17; Rear: 180/55 ZR 17
Reading back to front starting with rear:
- Rim diameter 17 inches
- R = carcass type = “Radial”. This is therefore a radial tire
- Z * is the velocity, so more than 240 k/ph or 149 mph. Simplified, this tire is capable of handling any speed this motorcycle can reach, within reasonable limits.
- 180 as well as the 120 on the rear is width of the tire in millimetres, so 18 cm and 12 cm for the rear; when fully inflated.
- 55 on the front tire is the measurement from inside the bead (which sits inside the wheel rim holding the tire within it) to the top of the tire is 55% of the tire’s width. In this example, 55% of 180 millimetres is 99 millimetres, or 3.9 inches. Same formula for 70 on the rear.
- TL: Tubeless tire
- TT: Tube Type – with tube
- TWI tread wear indicator (see image below) these can be different depending on manufacturer or tyre brand.
- 1501: DOT (Department of Transportation), the week of production – in the 15th week of 2001, the band produced. From the year 2000, the DOT four-digit, three digit before. Example: DOT 429 = 42nd week of 1999
- (73 W): 73 is the carrying capacity and “W” means permitted speed is over 270 km/ h
- M/C: Motorcycle and scooter tires
- (Arrow) means: direction – in this direction, the tire rolls for its mounted so it’s not put on backwards. If the tire were mounted incorrectly it could result in a dangerous situation, especially on a wet surface where the tire would be unable to dispel water away from the bike.
Do check particularly if your dealership is mounting your new tires it has been known to happen that in haste, the mechanic puts the tire on in the wrong direction. Furthermore, under inflation, one of the biggest mistakes people make with their tires is to exceed the maximum level indicated on the side wall. This leads to poor handling and premature wear. Be sure to measure pressure when the tire is cold.
Speed and Load Chart
If you have an older motorcycle vintage or classic, chances are you’ll have a diagonal tire tread such as pictured here:
Front wheel: 3.25 S 19
It is therefore a diagonal band with belt. The diagonal belt with belt is constructed as a normal diagonal band, but with carriers reinforced belt. This makes them heavy, but also for the load better equipped.
Reading from back to front.
- The last digit is the cross-section of tire rim to rim (rim diameter) in inches – so 19 is the rim diameter
- H means class speed to 180 km / h
- 3.25 is the tire diameter in inches
- Noted as tube tire and DOT rated
- Another example: Rear tire: 150/70 16 67 H
- H = class speed to 210 km / h
- 67=Capacity (see chart below): 307 kg. A motorcycle tire with 307 kg load capacity is
- B means Belt