But, if you buy a used bike privately you need to check them.
The letters and numbers on the sides of tyres provide a lot of information about sizing and performance, but also date of manufacture.
Although the numbering varies, there should be a series of letters and numbers in a box. The last four are the ones of importance. The first two indicate the week and the second two the year of manufacture.
Motorcycle manufacturers specify that all tyres over five years old should be checked, regardless of how much tread they have left. At 10 years old they should be replaced even if the tread is like new.
The reason for this is that the tyre compound hardens over time, diminishing grip which relies on a softness in the compound. You can tell a tyre is ageing by the presence of small cracks or crazing.
The tread on your tyres is designed to push water away, improving grip in even the worst conditions.
As soon as this tread starts to wear you’ll lose some of the grip and the bike will become more dangerous to ride.
Once the tread is worn below the legal limit of 1.5mm then you must change them. There are wear indicators on the tyres that show how close you are getting to this level. You can also use a tread depth checker to monitor the rate at which your tread disappears.
But this does not mean you need to wait until it reaches this depth. If you ride your bike hard or often ride in the wet, you should consider changing them at 2.5mm.
If it gets to the point where you can feel that your bike is not gripping the road properly then you know you have to change your tyres. By this stage you have probably left it longer than you should have.