You see your tyres every day, which makes it hard to catch the moment they’re finished. Most of the signs are visible to the eye, though, if you crouch down next to the bike.
The tread and the wear indicators
Inside the grooves of the tread there are small raised bars, the tread wear indicators or TWI. A small triangle or the letters TWI on the sidewall show where they are.
While the tread stands higher than the bars, there’s life left. Once it’s down level with them, the tyre needs changing. Check at several points round the tyre, because it doesn’t wear the same everywhere.
Cracks and age
A tyre can still have tread and not grip. Sun and cold harden the rubber over the years, even if the bike does few kilometres. Look for fine cracks on the sidewall and between the grooves. If the surface is shiny and feels hard under your fingernail, it will grip less in the cold and the wet. If you see a bulge on the sidewall, the tyre is damaged inside and has to go.
You’ll find its age in the DOT code on the sidewall: the last four digits are the week and year it was made. How many years a tyre lasts is for its manufacturer to say.
How it has worn
If the tyre has squared off in the middle, a lot of straight-line riding is usually to blame, such as the daily commute or the Egnatia motorway. Wear on the edges of the tread mostly shows how far you lean in the corners. Steps or ripples in the tread are not normal wear and want looking at.
Wrong pressure makes all of this worse: the tyre wears faster and more unevenly, and the bike handles differently. The right pressure is in the service book or on the bike’s sticker, and it’s often different with a passenger. Check it with the tyres cold, not straight after a ride.
If you can see any of this, give us a ring or book a tyre change. For what we do in the workshop, see the tyres page.