How to read your tires (and when to replace them)

Your tire is talking to you in code

Every motorcycle tire has a wall of numbers and letters stamped into the sidewall. Most riders ignore all of it. That is a mistake, because those markings tell you the exact size, the speed and load it can handle, how old it is, and where it was made. Read them and you buy the right tire every time and know exactly when to retire the old one.

A tire can look fine and still be dangerous. Rubber hardens and cracks with age even with plenty of tread left. Knowing how to read the date code is what separates safe riders from lucky ones.

Decoding the size and rating

A typical sidewall reads something like 180/55 ZR17 73W. Here is what that means.

• 180 is the tire width in millimetres.
• 55 is the aspect ratio, the sidewall height as a percentage of the width. So the sidewall is 55 percent of 180 mm.
• ZR or R tells you the construction. R is radial. The Z hints at a high speed rating.
• 17 is the wheel diameter in inches.
• 73 is the load index, a code for the maximum weight the tire carries.
• W is the speed rating. W means rated up to 270 km/h. Common ratings include H, V, W, and Z.

Match these to what your bike maker specifies. Putting on the wrong width or profile changes how the bike steers and can be unsafe.

Finding the age of your tire

This is the marking almost nobody checks. Look for the letters DOT followed by a string of characters ending in four digits. Those last four are the date code.

• The first two digits are the week of manufacture.
• The last two are the year.
• So 2419 means the 24th week of 2019.

Why it matters. Most tire makers say a tire should be replaced around six years from the manufacture date, and at most ten, regardless of tread. Old rubber loses grip and cracks. If your bike sat in a garage for years, those tires may be unsafe even if they look almost new.

When to replace, beyond the calendar

Age is one trigger. Here are the others.

1. 01Tread depth. When the tread reaches the wear bars, the small raised ridges in the grooves, the tire is legally and practically done. Many riders replace before that for wet grip.
2. 02Squaring off. High mileage commuters wear a flat strip down the centre while the edges stay new. A squared tire steers poorly and should be replaced.
3. 03Cracking. Cracks in the tread grooves or sidewall mean the rubber is perishing. Replace it.
4. 04Cuts, bulges, or embedded objects. A bulge means internal damage. Do not ride on it.
5. 05Flat spots or cupping. Often a sign of suspension or pressure issues as well as a worn tire.

Replace tires in the right order for your riding. A worn rear with a good front is common, but a fresh rear paired with a tired, hardened front can make the bike feel nervous. When in doubt, ask.

Match the tire to your riding

Sport, touring, sport touring, cruiser, dual sport, and track tires all behave differently. A touring tire lasts longer but grips less at the limit. A sticky sport tire grips hard but wears fast. Buying the right type for how you actually ride matters as much as the size.

Not sure what your bike needs or whether your current tires are safe? Our garage reads the codes, inspects for age and damage, and mounts and balances new tires properly. Book at our service shop or browse options in the tire section.