There’s an old adage that states “a stitch in time saves nine.” It generally suggests that tending to small problems before they get worse prevents further work later on.
In this post, we discuss how to check tyre tread depth, what the legal limit is, and what causes uneven tyre wear.
A tyre tread makes up the little grooves and ridges that run along the circumference of a tyre’s rubber surface. These might not look like much, but they’re absolutely essential.
Each one of these grooves offers grip to the road surface, allowing you to brake and manoeuvre safely. As tread depth decreases, a tyre’s performance deteriorates, making it difficult to transmit traction to the road effectively. Allow your tyres to become over-worn and you run the risk of greater stopping distances and less control.
A deep tyre tread will also quickly channel water away from the rubber, so it doesn’t lose contact with the road. This makes tyre tread depth essential when roads become wet and hazardous, as it prevents aquaplaning.
The tread depth of a new tyre is approximately 8mm, but naturally this becomes shallower over time. Causes of tread deterioration include:
While the typical lifespan of a tyre will differ depending on the above factors, it’s generally considered prudent to order a replacement once the depth reaches 3mm (RoSPA found that this is the point at which stopping distances start to increase dramatically). Similar research suggests over or under inflating a tyre reduces the traction between the rubber and road, which leads to increased tread wear and greater stopping distances.
“If your vehicle starts to lose road grip or doesn’t handle correctly in adverse weather conditions, you should consult a tyre specialist ASAP.”
UK law stipulates that a car should have a minimum tread depth of 1.6mm in a continuous band around the central three-quarters of the tyre. The same rule applies to goods vehicles, such as vans, trailers and caravans that don’t exceed 3500kg.
While UK tyre law states that a wheel should have a minimum tread depth of 1.6mm, most motoring experts would recommend replacing a tyre once the tread gets to 2-3mm. This is confirmed by RoSPA’s study, which found stopping distances increase by 44.6% on smooth concrete at the legal minimum tread depth.
The most accurate way of checking your tyre’s tread is with a purpose-made tool called a tyre tread depth gauge. This is what the technicians at Tyres On The Drive use to quickly and accurately measure the depth of an individual tyre groove. Many of these handy gadgets also allow you to check car tyre pressure. If you have one to hand, simply insert the probe bar into the groove and then push the shoulders flush with the tread.
If you don’t have a tyre tread depth gauge, you could check the tyre’s tread wear indicators (TWI), or wear bars. These are evenly spaced through the main grooves in the tyre tread and allow you to take a visual reading. In some instances, a small triangle marking will denote the position of the tread wear indicator. If the indicator is flush with the level of the tread, then the tyre should be replaced.
You will often hear people refer to ‘the 20p test.’ This is the quickest and easiest way to check your tyre’s tread depth – but also the least accurate.
Living in the UK means having to contend with adverse weather conditions on a regular basis, so it’s best to check your tyres frequently to make sure they’re fit for use. But how often is frequently? Here’s what Daniel Bezer, tyre expert at TOTD, recommends:
“Carrying out basic but essential tyre checks can mitigate many potential issues drivers might suffer. This could include anything from preventing delays and additional expense to dangerous cases of injury. At TOTD, we recommend checking your tyres once every couple of weeks and especially before long journeys to minimise the risk of tyre-related incidents.”
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