Inspecting tyre tread depth is an important check to make on your car. Failure to do so could compromise safety when driving and can put you at risk of fines and penalty points.
In this guide, we explain everything you need to know about tyre tread depth, including what it is, how to check tyre tread depth, what can cause wear, and when the right time is to replace your tyres, so you can drive both safely and compliantly.
What is Tyre Tread Depth?
The tread is the rubber on tyres that makes contact with the road. Over time, the tread reduces as the tyre wears, decreasing the tyre’s capabilities to grip the road. Tyre tread depth, therefore, is the measurement in millimetres (mm) of the remaining tread from the surface to the bottom of the tyre’s grooves. This measurement indicates how much usable grip the tyre has remaining before it becomes unsafe or illegal to drive on. Depending on the manufacturer and type, a brand new tyre commonly has a tread depth of 8mm.
What is the Legal Tyre Tread Depth in the UK?
In the UK and Europe, the legal minimum tread depth for cars is 1.6mm across the central three-quarters of the tyre. It must meet this minimum across its entire circumference.
Did You Know? Bald tyres — a tyre that has worn tread or no tread left — are one of the primary reasons for MOT failure, so it is vital you check your tyres regularly.
What Happens if the Tyre Tread is Below Minimum Depth
If your car tyre tread is below the minimum depth, you are at risk of fines and penalty points. For each tyre below 1.6mm tread, you risk a £2,500 fine and three penalty points on your license. If all four of your tyres are below the minimum, you could face a court summons, a £10,000 fine, and 12 penalty points, resulting in a driving ban.
Aside from the legal repercussions, driving on tyres with little tread is dangerous and can compromise safety. For instance, it can mean:
- Increased likelihood of punctures
- Increased risk of aquaplaning
- Reduced braking performance in wet conditions
- Difficulty gaining traction in snowy or icy weather conditions.
If you are involved in an accident caused by driving on illegal tyres, your insurance could be invalidated.
These factors all reinforce the importance of regularly checking tyre tread depth.
How to Check Tyre Tread Depth
There are three methods for checking tyre tread depth as detailed below.
1. The 20p Test
This is perhaps the easiest way to check tyre tread, and all it requires is a 20-pence coin. Take the coin and slot it into the tread grooves where the tread is at its most shallow. If you cannot see the coin’s outer band, your tyre is above the 1.6mm legal limit. But, if you can see the band and that section of the coin is still visible, the tyre could be below the limit and therefore unsafe. In this instance, it is best to get the tyres inspected by a mechanic.
This simple test should be performed approximately every two weeks, as well as before any long journeys.
2. Tyre Tread Wear Indicators (TWI)
The second test is by examining Tread Wear Indicators (TWI) on your tyre. The majority of modern cars have bars or blocks that are moulded into the tread grooves at regular intervals around the tyre. If the tyre is flush with these bars, it will need to be replaced urgently as the tread falls below the legal limit.
3. Tyre Tread Depth Gauge
The third and final method is by using a tyre tread depth gauge. This is a tool specifically for measuring the depth of individual tyre grooves. All you need to do is place the tool on the tyre, and it gives you the depth measurement in millimetres.
Did You Know? Both analogue and digital tyre tread depth gauges are available and are an effective way to check your tyres.
What Can Cause Tyre Tread Wear
Car tyres naturally wear down over time and use, but other components at play can impact tread wear, including:
- Misaligned tyres
- Driving with excess loads
- Incorrect tyre inflation
- Worn suspension parts
- Aggressive driving style, such as rapid acceleration and high-speed cornering.
When is the Right Time to Replace Tyres?
While the legal minimum requirement is 1.6mm for tyre tread depth, it is highly suggested that tyres be replaced before they reach this minimum. Experts recommend, for safety purposes, that once the tyre tread depth reaches 3mm, it is time for a tyre replacement.
Top Tip: Check out our article to find out everything you need to know about car tyres.
Professional Tyre Replacement: Pantech Auto Technicians
Consistently checking tyre tread depth is essential for your safety and compliance. If you are unsure how to measure tread depth by yourself, or would like assistance with replacing a worn tyre, Pantech Auto Technicians are on hand to help.
As a Guildford MOT and service centre, we offer a large selection of tyres to suit your car (and your budget), so you can replace tyres without paying extortionate prices. All of our prices quoted include:
- Disposal of the worn tyre
- Computerised balancing
- The tyre fitting itself.
Having your tyres inspected and changed by a specialist is always the safest and most reliable option.
Contact us at Pantech Auto Technicians today to get further advice on tyre tread wear or to book your car for a tyre fitting in Guildford.
