Legal: The Legality of tyre mousses


Just how likely are you to be stopped if you’re riding with tyre mousses? And are you even breaking the law? Andrew Dalton explains it all…


I read your previous article about mousses with interest. Do the police actually have the power to detain my bike and check whether or not I have mousses in? I keep valves in my wheels and there is no obvious method of testing whether the tyres have mousses in them.



For those of you who missed the piece on the law of knobbly tyres, I was of the view that mousses, whilst useful, did not meet the construction and use tests and are, therefore, technically, illegal. John asks the question “so, will I be caught?”

The police do have the power to stop you for any reason, but being mindful not to be accused of harassment, they usually record one, such as asking you to produce documents. For a bike which has been out on the lanes it could be to stop you to tell you that your number plate is obscured, and at this point, you have the ‘attitude test’.

If you are pulled over by an ordinary car (i.e. not a police pursuit vehicle) and the officer gets out of the car wearing a black rather than a white cap then the reality is that whilst they have exactly the same powers as a road traffic officer, with one exception relating to high-speed pursuits, they are unlikely to be fully versed in road traffic law.

Obviously, they will know that you need to be displaying a number plate and the police national computer check will soon reveal whether or not your bike is insured and taxed. All constables have a working knowledge of road traffic law.

If you catch a road traffic officer on a bad day and you are running your bike on mousses you could be in for a significant amount of inconvenience, but not a huge amount of difficulty.

If the officer thinks that your tyres are suspicious and he puts a pressure gauge on them, a tyre with mousses will read zero. The police officer would then have grounds for impounding the vehicle as, in his opinion, it would be dangerous to take on the road. The tyre itself is unlawful under the construction and use regulations.

The police officer would be well within his rights then to take them for further examination, either by an officer authorised for vehicle inspection, or another suitably qualified civilian vehicle examiner to explain this mysterious 0 psi. The police officer would be using his powers in a way which a magistrates’ court would find reasonable.

Depending on the mood of the officer, he could either impound the vehicle there and then, tell you that if you moved the bike again you would be committing a further road traffic offence, and if you started the bike up he would nick you for a further offence of taking a vehicle onto a road with defective tyres. He could tell you to have the vehicle recovered, or he could issue you with a vehicle rectification notice. Whichever way he does it, he can make your life difficult.

If he does not have a tyre pressure gauge then there is no obvious defect on the machine, the machine is not objectively dangerous, and he would have no such powers. In short, you take a calculated risk when you ride a bike on the road or the byways with mousses.

The chances of an officious police officer having the knowledge and equipment to make a charge stick are small. However, if you combine mousses with a small and illegal number plate, a bad attitude, a noisy pipe, and inconsiderate riding, then you make yourself ‘nick-bait’ and being nick-bait is best avoided.