Tread depth, age, and when to replace a motorcycle tyre
For a motorcycle over 50cc the UK legal minimum is 1mm of tread across three quarters of the breadth of the tread pattern, with visible tread on the rest. For 50cc and under, all the grooves of the original pattern must be clearly visible. Both are the point at which you are breaking the law rather than the point at which the tyre stopped being any good, and on two wheels that gap matters.
The legal minimum in the UK
For a motorcycle over 50cc, or its electric equivalent, the requirement is 1mm of tread across three quarters of the breadth of the tread pattern, with visible tread on the remaining quarter.
For a machine of 50cc or under, the rule is different and stricter in spirit: all the grooves of the original tread pattern must be clearly visible. There is no depth figure, which means a tyre worn smooth but not quite bald is still illegal.
Both are minimums rather than targets. Wet grip falls away well before you reach either.
Why the legal figure is the wrong target
A motorcycle has two contact patches, each about the size of a credit card, and no way to stay upright if one loses grip. The margin that a car driver can afford to run down, a rider cannot.
Wet braking degrades steadily as tread depth falls, and it falls off a cliff in the last couple of millimetres. On an electric machine with instant torque and a heavier kerb weight, that last couple of millimetres is where the trouble is.
Age, and the thing riders miss
Rubber hardens with time whether or not the machine is ridden. A tyre with plenty of tread and a date code six or seven years old is near the end of its useful life, and it will feel it in the first cold wet corner.
Machines that sit through winter are the ones this catches. Check the DOT code as well as the depth, and check both before the first ride of spring rather than after.
What to look at besides the depth
Squaring off. A rear worn flat across the centre and round at the shoulders will tip into corners strangely and is finished as a handling component long before it is finished as a legal one.
Cracking in the grooves or the sidewall. That is age, not wear, and it is a replacement.
Cupping or scalloping on the front, which usually points at suspension or pressure rather than at the tyre.
Common questions
- Is the legal minimum a safe minimum?
- No. It is the point at which you are committing an offence. Wet performance has degraded long before it.
- How old is too old?
- Most manufacturers suggest replacing at five to six years regardless of tread, and inspecting annually after that. The DOT code gives you the date.
- Do I have to replace both at once?
- No. Replace what is worn, and on an electric machine that will usually be the rear.
Last checked 2026-09-22. Where this page and your own vehicle disagree, the vehicle wins.