Part-worn tyres: are they safe and should I buy them?

They should have at least 2mm of tread across their width and around their circumference, and they should be clearly and permanently marked ‘part-worn’ in upper-case letters at least 4mm in height on their sidewalls. 

Although these regulations are very straightforward, many part-worn-tyre suppliers are known to flout them. If you are considering buying a set of used tyres, make sure the vendor is compliant with these laws - and remember, tyres that do not meet these minimum requirements could cause you to have a very serious accident. 

How long should part-worn tyres last?

Second-hand tyres will not last as long as new ones. You will have to replace them much more often, so the savings will be less substantial than they might first appear. 

A new tyre might have as much as 8mm of tread, whereas a part-worn one might have only a quarter of that. It will therefore be fit for only a few hundred miles and will need replacing before long. 

Pros of part-worn tyres

The big advantage of part-worn tyres is that they cost less than brand-new ones. Typically going used can save hundreds of pounds, especially when buying four tyres.

What’s more, by buying a set of used rubber, you might be able to afford a higher-quality tyre from a big-name brand, rather than a budget tyre from a manufacturer you’ve never heard of.

There's also the environmental benefit of buying something that has already been used and seeing it through to the end of its life cycle.

Cons of part-worn tyres

Many part-worn tyres are potentially unsafe. It should be considered that if somebody has removed a set of tyres from their car, they have done so because they no longer consider them to be safe. If those tyres aren’t good enough for another driver, are they really good enough for you? 

With less tread depth than a brand-new tyre, part-worn tyres will generate less grip, particularly in the wet. That means your car will have less traction and - more importantly - less cornering and braking grip. 

A survey carried out by TyreSafe found that up to 98% of used tyres sold in the UK did not comply with the regulations, while 34% could be considered dangerous. However, even a tyre that does satisfy the regulations could be harbouring a nasty secret, whereas a brand-new tyre will not. 

During a government investigation, it was found that 85% of part-worn tyres were non-compliant as they were incorrectly marked. Eleven per cent of part-worn tyres were found to be more than 10 years old. 

They could also have hidden damage. One part-worn tyre Autocar was shown had been repaired twice (pictured below), both on the shoulder of the tyre and close to each other. 

Gordon said, although not illegal, this is bad practice as any repairs to the shoulder of the tyre is considered dangerous given the issues – such as bulges – that could arise.

What made this particular case worse was the repairs were only visible from the inside of the tyre, meaning any buyers would be unaware of the danger.

“I understand that people are struggling for money, and, as new tyres are an expensive purchase, part-worn may be an appealing option, but I would always recommend buying new,” said Gordon.

Here are a few more problems the investigation into part-worn tyres found: 

- Some tyres had cuts in the primary tread area, which were deep enough to expose the metal cords 

- Tyres fitted incorrectly, with the outside sidewall of the tyre fitted to the inside of the wheel rim 

- Abnormal bulges in one of the sidewalls  

- Repairs that did not conform to British Standard, including a 'string'-type plug that does not form a permanent seal and may not be secure 

- Hard objects penetrating the tyres 

Alternatives to part-worn tyres

In years gone by, remoulded tyres, or retreaded tyres, were a popular solution. Remoulds are still legal in the UK, so long as they comply with strict regulations, and if manufactured with care they needn’t be significantly less safe than new tyres. 

Retreading a tyre involves stripping the tread and sidewall from a used tyre (the structure of which should be in good condition) and applying new rubber to the carcass. As budget tyres from the Far East have become more commonplace, though, remoulded tyres have become less popular.

Should I buy part-worn tyres?

If we could guarantee that part-worn tyres were completely safe and compliant with the regulations, there would be little reason to be wary of them. However, as those TyreSafe figures demonstrate, there are no such assurances.

If there is one area of car maintenance on which you shouldn’t skimp on cost, it’s the only part of the car that actually makes contact with the road - the tyres. Ultimately, it is down to personal choice and whether you are willing to accept that it could offer a false economy, as well as be potentially dangerous. 

Paul Heaton, R&D director at Pirelli UK, feels very strongly about part-worn tyres. "All part-worn tyres are required to be thoroughly inspected internally and externally before sale, but in reality far too many have not been checked at all," he says. "Many tyres are sold with structural damage that should mean the tyre is scrapped. The best course of action is simply to avoid part-worn tyres."