Essential Tyre Checks When Buying A Used Car

One thing to make sure of when buying a used car is that all its vital parts are in good working order – and tyre checks are one of the steps you can take.

There’s a lot to think about when buying a used car. Can you afford it? How many miles has it done? Is there anything from its service history you need to know? One thing you’ll want to make sure of is that all its vital parts are in good working order. Tyre checks are one of the steps you can take as part of this – but do you know what to look for and what the danger signs are?

Dave Jones, a tyre technician, was collecting an item he’d bought online one day. While out, he spotted the tyres on a 2-year old car for sale. The reason the tyres caught his eye is because the pattern on them had been discontinued long before the car had been made. On closer inspection, Dave noticed the tyres carried a 3-digit number that revealed they had, in fact, been made before 2000 and were at least 16 years old.

It seemed the seller had swapped the car’s original tyres – which were newer and more expensive – for a set of older ones. If you had been buying that car, would you have been able to tell? No? You wouldn’t be alone.

We’ve put together some advice on easy tyre checks you can do yourself – to make sure the next used car you buy doesn’t come with something unexpected.


Why do I need to check the tyres?

This can depend on who you’re buying from. Any car sold by a dealer must be roadworthy, as described, fit for purpose and of satisfactory qualify. They can’t legally sell a car fitted with tyres that aren’t in good condition and don’t meet the legal limit.

Private sellers also have to make sure the car they’re selling is roadworthy, but there might be more reason to check.

As the tyres are the only part of your car in contact with the road, the safety of you, your passengers and other road users depends critically on your tyres being in good condition and correctly inflated. If they’re in poor condition, there are so many ways in which you’re putting yourself at risk. Worn tyres increase your chances of suffering a blowout and can also cause the car to handle poorly. These can have potentially catastrophic consequences.

If staying safe on the road isn’t enough of a reason, poor quality tyres will hit you in the pocket too. Not only do you have to buy new tyres that meet legal requirements, getting caught driving with them will land you with penalty points and a hefty fine… per tyre. All this adds up to one bad deal if you buy a used car with tyres that aren’t up to scratch.


How do I check tyre tread depth?

One of the easiest things you can do is to check tyre tread depth. All you need is a 20p coin. The tread on car tyres must be at least 1.6mm throughout a continuous band in the centre 3/4 of the tread, and around the whole circumference. 

To see if your tyres hit the minimum legal tread depth, pop a 20p coin into the main tread groove of your tyre. If the outer band of the coin is hidden by the tread (i.e. you can’t read the words ‘Twenty Pence’ or ‘Elizabeth II’), your tyres should be good to go in the eyes of the law.

Bear in mind the band on a 20p piece is closer to 2mm than 1.6mm, so this check isn’t definitive. It’s best to check the tread-wear indicators, which are small lumps in the base of the main tread grooves. The top of this is at the legal limit of 1.6mm so, if they’re flush with the outside surface of the tyre, it’s on or below the legal limit.

If the tread depth is less than this on the car you buy, then bring this up with the seller.


How do I check tyre pressure?

Having a pressure gauge to hand when you visit a dealer or private seller makes a car tyre pressure check simple to do. Take off the valve dust cap and place the gauge into the valve’s stem – pressing down to get your reading. Bear in mind you can get a metric or imperial reading. Once you have this figure, compare it against the car’s recommended tyre pressure.

You can find this on a sticker inside the driver door or in the owner’s manual.

Check all 4 tyres and measure the readings against the ‘cold’ number if it’s unlikely the car has been driven in the last 2 hours. If the pressure is lower than recommended, then air could be escaping from the tyre somewhere. If it’s higher, has the seller over-compensated to disguise a fault? Either way, driving on under or over-inflated tyres increases wear and risks causing further damage.


What signs of wear and tear should I look out for?

If you’re a reasonably careful driver, you might expect to get 20,000 miles out of front tyres on a front-wheel-drive car, and 40,000 miles for rear tyres. Over such long distances, you can expect the tyres on a used car to show some signs of wear and tear. But it’s important to look out for these signs to make sure you know what condition the tyres are in.

Tyres will wear unevenly if they’re either over- or under-inflated. If you spot this, it’ll tell you something about how well the car’s previous owner has looked after it. The tyres may still be legal, but they’re not going to last as long as they would if the wear was even across the width of the tread.

A bulge or lump in the tyre’s sidewall, which could be the result of hitting a pothole or kerb, is potentially very dangerous. The car isn’t roadworthy and the tyre should be replaced before you drive away. In the MOT test, a bulge or a lump in the tyre is considered a ‘dangerous’ defeat – do not drive until it’s repaired.

While checking for lumps and bulges, you should also look for any cuts or cracks in the tyre’s tread or sidewall. Cuts can be caused by potholes, driving over sharp objects (e.g. glass) or even parts of bodywork hanging loose. Cracks can also be caused by an impact, but can be a result of age or long-term exposure to the elements. Any crack that’s deep enough to expose the tyre’s internal structure would mean an MOT failure. 


What about the spare tyre?

Take a look in the boot (or under the car). Is there a spare tyre? If there is and it’s worn, the chances are it’s been fitted in place of a damaged road wheel, which has been put in the carrier rather than being renewed/repaired. Check any spare like you would the 4 on the car. You’ll want to make sure it’s in roadworthy condition should you ever need it.

If there isn’t a spare, it could tell you that it has already been used due to a problem with a previous tyre. Not all used cars will come with a spare tyre, though. It’s not a legal requirement and isn’t checked as part of an MOT, so the absence of a spare wheel isn’t necessarily a problem.


Are there any other questions I can ask about the tyres?

If there’s nothing amiss after performing these tyre checks and you’re buying from a private seller, there’s no harm asking a few more questions to get a better idea of what you can expect from the existing tyres:

  • How many miles has the car done on the current set of tyres?
  • When was the last time they were inflated?
  • Have there been any problems such as uneven wear?

Bear in mind a dealer is unlikely to know the answers to these questions, if at all, as they won’t have as deep a knowledge of the car’s history as a private seller would.


This information, together with your own checks, should give you the confidence that you won’t have any unexpected issues with your tyres. But if you’re still not satisfied, why not ask us? Our pre-purchase car inspection service includes wheels and tyres as standard, which means you have the added confidence of having an experienced AA engineer look over them for you.

Image courtesy of iStock.


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