Many drivers in the United Kingdom are familiar with the 20p trick for tyres, but few realise just how valuable this simple test can be in keeping vehicles safe and roadworthy.
The 20p test isn’t just an old motoring tip, it’s supported by organisations such as the RAC Limited and serves as an easy way to check that your tyres meet the legal tread depth requirements. As a company dedicated to tyre safety and expert advice, Mobile Tyres explains exactly what the 20p trick involves, why tyre tread depth is so significant, and how you can use this method to prevent fines, insurance issues, and accidents.
Understanding Tyre Tread Depth and the Law
Tyre tread depth refers to the vertical measurement between the top of a tyre’s rubber tread and the bottom of the main grooves running around the tyre.
In the UK and Europe, the law states that all car tyres must have a minimum tread depth of 1.6mm across the central three-quarters of the tyre’s width and around the entire circumference of the tyre. The legal minimum tread depth helps ensure that tyres grip to the road effectively, especially in wet or slippery conditions.
The reason for this regulation is straightforward. Tyre tread pattern and depth help channel water out from underneath the tyre when driving on wet roads, significantly reducing the risk of aquaplaning and affecting your vehicle’s braking distance.
Without enough tread, tyres could become much less effective in rain, leading to longer stopping times and poorer steering control. Drivers caught with illegal tyres could face a fine of up to £2,500 and three penalty points per tyre. Replacing your tyres as soon as they wear down is not just about compliance but safety for all road users. If you are not sure whether your tyres are roadworthy, we have compiled a list of 5 signs that your tyres need replacing.
Why Tyre Tread Matters for Every Car
Tyres are the only contact between your vehicle and the road. The tread grooves, cut into the tyre surface, are designed to provide grip, especially in wet weather. Low tread depth means less rubber between your car and the surface, which increases the risk of skidding, aquaplaning, and losing control, especially when you need to brake sharply or steer around obstacles.
Tread depth under the road traffic limit doesn’t just affect safety; it impacts insurance too. If your car tyres don’t meet the legal minimum tread depth, your insurance could be invalid in the event of an accident. During every MOT test across the United Kingdom, testers check tyre tread and will fail vehicles with illegal tyres, meaning new tyres will be needed before the car can pass.
The 20p Tyre Trick – An Easy Way to Check Your Tyres at Home
The 20p trick, known by some as the 20p coin trick or 20p tyre test, provides a simple way to check if your tyres are safe and legal. All you need is a standard 20p coin, which is about 2.7mm thick with a raised outer band. Here’s how to conduct the 20p test:
Simply place a 20p coin into the main tread grooves of your car tyre. Make sure you check the central three-quarters of the tyre, as this is where the law requires the minimum tread depth. If the outer band of the coin, the bit with no writing, disappears entirely within the tread when inserted, your tyres meet (or exceed) the legal tyre tread depth. If you can see any part of the outer band, your tread is below the legal minimum of 1.6mm, and your tyres could be unsafe or even illegal.
This trick to check tyre wear is recommended by tyre professionals as an easy check for all car owners. There’s no need for fancy equipment; a simple 20p is all you need. The 20p tyre trick works on most tyres fitted to cars in the UK and Europe and can be carried out in under a minute, making it a leading, easy trick for those urged to check their tyres regularly.
How to Carry Out the 20p Hack on All Four Tyres
Checking your tread depth isn’t just about a single tyre. The law in the UK requires all four tyres to meet the minimum tread depth. To make sure your car remains legal and safe, conduct the 20p coin test on each tyre, paying attention to the central three-quarters of the tread across the entire circumference of the tyre. Insert the coin into several tread grooves on every tyre for a more accurate reading, as wear isn’t always even. If the tread is flush with the coin or if you can see the rim, it’s a clear indication that the tyre needs replacing.
The majority of tyre wear happens gradually, so even if only one spot is under the limit, the tyre is considered illegal. Low tread depth may also signal other issues like incorrect tyre pressure or wheel alignment. Tyre professionals recommend checking your tyres each month and before long journeys.
Tread Depth Gauges and Other Methods Compared to the 20p Test
Some motorists and tyre specialists use tread depth gauges, which measure tread to a fraction of a millimetre for a precise reading. While these are effective, the 20p trick remains the fastest way of checking tyre tread for most drivers. The 20p test is a simple way to check and only requires any twenty pence British coin, rather than expensive tools.
The 20p tyre test is especially useful if you don’t regularly visit a garage or tyre shop. With so many drivers busy with daily life, using the 20p to check their tyres helps avoid the risks of worn tyres passing unnoticed until an MOT test or, worse, until you have an accident on a wet road.
Why Regularly Checking Your Tyre Tread Depth Is Key
Tyre tread depth impacts everything from braking distance to your risk of aquaplaning. New tyres typically have about 8mm of tread. As tyres are used day after day, the tread wears down, particularly on the driven wheels. When the tread depth gets close to the legal limit of 1.6mm, it’s recommended to think about getting replacements fitted. Many tyre professionals suggest considering a minimum of 3mm of tread for optimum wet weather grip.
If you find your tread is below the legal minimum or approaching it after conducting the 20p hack, arrange to change your tyres promptly. Tyres worn below the legal limit may not just land you with a fine, they could put everyone in danger. Driving with tyres under the permitted limit means your vehicle won’t steer or brake as it should, especially when it matters most on slippery or icy roads.
What Else to Check When Looking at Your Tyres
Checking the tyre tread depth is only part of keeping your car tyres safe. Inspect tyres for bulges, cracks, or objects stuck in the tread pattern. Make sure tyre pressure matches the manufacturer’s recommended values, as under-inflated or over-inflated tyres will not grip the road as designed, can wear faster, and may even blow out. It’s wise to check your tyre pressure as often as your tread, especially before longer journeys or changes in weather conditions like heavy rain or a switch to cold temperatures.
The main tread on each tyre must meet this minimum for every car in England, as well as the rest of the United Kingdom and Europe. Don’t forget that testing with a coin to check the tread should be done all the way around the tyre, not only at one point, since tread wear can be uneven depending on how your vehicle is used.
Common Questions About the 20p Coin Trick
Can I use any coin? The 20p test relies on the twenty pence British coin, whose outer rim is approximately 2.7mm high. The area without lettering makes it a reliable reference for the legal minimum. Other coins don’t match this thickness and so give inaccurate results.
Does the 20p test work for all tyres? Yes, the 20p tyre trick works on all car tyres used on roads in the UK, as the groove of the tyre is designed with the legal limit in mind. Racing slicks and off-road tyres may require different checks, ask a professional if unsure.
What if only part of my tyre is worn? If the tread is low only in certain spots but is above 1.6mm elsewhere, the tyre is still classed as illegal. The law requires continuous minimum tread across the entire circumference of the tyre for at least the central three-quarters in width.
Why do tyre professionals recommend the 20p test? The 20p test is easy, quick, and gives a good indication that the tyre meets the legal minimum tread depth, which helps your tyres grip in wet and dry conditions. For more accurate checks, or if you’re unsure, always ask a professional or use a tread depth gauge.
Can illegal tyres affect insurance? Driving with illegal or worn tyres could lead to insurance claims being reduced or rejected. Always make sure your tyres pass the 20p test before the risk becomes reality on the road.
The Importance of All Four Tyres Being Legal
Some drivers only worry when one tyre looks almost bald, but the law treats each tyre separately. If all four tyres are worn below the limit, fines can multiply fast, three points and up to £2,500 per tyre. That’s more than just a dent to the wallet; it can cause licence loss and invalidate insurance cover. This highlights the value of the 20p tyre test. When you check your tyres, always carry out the 20p hack on all four tyres, including your spare if fitted.
Tyres wear at different rates, depending on how and where you drive. City driving, road types, frequent heavy braking, and even tyre pressure can accelerate tread wear. Develop the habit of checking your tyre tread depth regularly. Carry a 20p in your glove box, and you’ll always have a simple way to check tyre condition wherever you are in the UK.
Why Mobile Tyres is Glasgow’s First Choice for Tyre Safety
When your car tyre fails the 20p coin trick or you’re unsure about tread wear, getting new tyres fitted quickly saves hassle and risk. Mobile Tyres, located at 191 Broomloan Road, Ibrox, Glasgow, is trusted by hundreds of motorists and local businesses for 24/7 mobile tyre fitting across Glasgow and Central Scotland. Offering rapid response, transparent pricing, our tyre professionals do replacements at home, work, or roadside. Mobile Tyres takes the stress out of looking after your four tyres. The team will supply and fit new tyres, safely dispose of worn ones, and always check tyre pressure and general safety on every job.
Mobile Tyres operates independently, with a commitment to keeping cars in the UK rolling safely at any hour. With a top-rated reputation, decades of technical experience, and an all-inclusive service, Mobile Tyres helps you avoid the risks of driving with tyres below the legal minimum tread depth. The company supports drivers through scheduled appointments, emergency call-outs, and expert tyre checks with every visit.
Contact Mobile Tyres for Expert Help With Tyre Checks and Mobile Fitting
If the 20p tyre test shows your tread is approaching or below the legal limit, don’t wait for your next MOT test, roadside check, or a near-miss in the rain. Mobile Tyres can supply and fit replacement car tyres anywhere in Glasgow and most of Central Scotland, day or night. Whether you need a single new tyre or a full set fitted on-site, Mobile Tyres comes to you – fast, convenient, and professional.
For fast mobile tyre fitting, expert checks, or tyre advice, contact Glasgow Mobile Tyres at 191 Broomloan Rd, Ibrox, Glasgow, G51 2JE or call 0800 699 0664. Stay safe, keep your tyre tread legal, and trust Glasgow’s local mobile tyre specialists to keep your car ready for any journey.
