Decoding Motorcycle Tire Codes

Only two small tire contact patches connect a motorcycle to the road. Their combined area is less than the sole of a boot. Acceleration to 100 km/h in 3 seconds, grip in corners at 250 km/h, braking from 300 km/h to zero: all this happens on the tiny area of these two patches.

Tires are hugely important for a motorcycle's performance and the rider's safety.

When you change the type or model of tire, the motorcycle's behavior on the road changes. So it's important to choose tires correctly. The required tire parameters for a specific motorcycle are given in the manual. The make and model of tire are often specified. In this case the characteristics of the specified model are taken as the required ones.

Types of motorcycle tires

Sport: sport tires. They have the best road grip and the shortest service life. They wear out in less than 3,000 km. The rubber compound is optimized for high temperatures. The tire shape is designed to keep a sufficient contact patch in deep corners at high speed. At insufficient temperature the tire's performance drops sharply. Using such tires in the city is unsafe because the operating temperature can't be maintained. In racing, tire temperature is maintained with warmers and warm-up laps; in the city it's very hard to warm up tires, since you have to stop and can't constantly keep up a high speed.

Sport Street: tires for aggressive street riding. They let you take corners at high speeds with a deep lean. They don't need warming up beforehand, but their performance deteriorates when overheated.

Sport Touring: they have the best balance between road grip and service life.

Touring: they have the longest service life and good grip at low rubber temperatures. They are suitable for cold climates. They aren't designed for deep corners at high speed.

Off-road: they have a knobby, deep tread. They are designed for stable riding on dirt, mud, sand and gravel. Stability is reduced on asphalt.

Information on the tire sidewall

The tire sidewall has all the necessary information: tire type, size, cord construction, speed rating, maximum load, maximum pressure, country of manufacture and certification, manufacturer and model, date of manufacture and fitting marks. For example:

180/55 ZR-17 (73W) TL

180: width in millimeters

55: height as a percentage of width

Z: speed rating. See the table.

R: cord type. R is radial. D is diagonal (bias). Radial cord is lighter and used on sport bikes. Diagonal cord handles impact loads better and is more suitable for heavy cruisers.

17: rim diameter in inches.

73: load index. The load in kilograms the tire is rated for.

W: speed index. The speed the tire is rated for. Tires with a low speed and load index are cheaper, but if the rated parameters are exceeded, the tire may burst.

TL: tire type abbreviation. TL (TubeLess) is tubeless. TT (Tube Type) is used with a tube.

The maximum pressure is shown on the sidewall in kilopascals and pounds per square inch. For example, 290 KPA (42 PSI) COLD means the corresponding maximum cold pressure. An underinflated tire has a much shorter service life and worse performance. So besides a daily visual check, you need to check the pressure with a gauge, especially before long trips and at least once a week. One of the sidewalls may have a yellow or red dot. Manufacturers recommend lining up the yellow dot with the valve. The yellow dot marks the lightest point of the tire in terms of static balance. Strictly speaking, it should be lined up with the heaviest point of the rim. But on a true rim this point is always the valve. We have seen a red dot only on Metzeler tires, and the manufacturer also recommends lining it up with the valve.

An arrow labeled Rotation, or just an arrow, indicates the direction of rotation.

Front, F, Rear: indicates the front or rear wheel. Also relevant for some scooter models.

The tire's date of manufacture is shown by digits in an oval. The first two digits indicate the week number. The next one or two digits indicate the year. For example, 3507 is the thirty-fifth week of 2007. The older the tire, the higher the risk that it may have deteriorated through improper storage. In various countries it is prohibited to sell tires older than 3 or 5 years. But using them isn't prohibited. So when buying tires older than 5 years, assess their condition carefully.

SIDEWALL NYLON1 TREAD NYLON 2+ARAMID 2: indicates the type and number of cord plies (nylon, polyamide or steel).

DOT, E with a number, ECE: certification information.

Replacing tires

Tires need replacing when the wear has reached at least one indicator (small ridges in the tread grooves). An old tire without mechanical wear can lose its properties due to long-term exposure to sunlight, low temperatures or sharp temperature changes. The rubber can harden, and microcracks or visible cracks can appear on it. In that case the tire needs to be replaced.

For clarity, watch the video with an example!

Load index

Speed index