At the same time, however, in some European countries, such as Austria, winter tires with a residual tread depth of less than four millimeters are legally considered summer tires and are not even allowed to drive on certain roads. You may not know it, but tire manufacturers add tread wear indicators that are poured into the tread grooves. This is a way to indicate if a tire is worn beyond the minimum safety limit. They`re really easy to use – if you can see them, you`ll need to replace your tires. The marks on the sidewall of the tire will help you find them. Road or highway tires, including those on crossover SUVs, should be replaced at least every 10 years, including spare tires. This upper age limit applies if they have been properly cared for during routine checks, have not been damaged and if the tread meets the minimum depth requirements. We recommend replacing off-road SUV tires at least every five years if they are frequently used off-road, or having them checked annually once they reach the five-year mark. Off-road SUV tires don`t last as long as regular vehicle tires, as the tread wears out much faster with the weight of the vehicle and the difficult terrain it traverses. To learn more about replacing your SUV tires, click here. Driving with tires that tread below the legal limit – or worse, that are bald – is dangerous.
Since performance is designed for durability, at Michelin we recommend using our tires up to the legal limit of 1.6 mm. Legal Tire Limit: As briefly mentioned earlier, the minimum legal tread depth is 1.6mm, but many tire and safety experts believe that this is not enough to ensure safety. Most experts recommend that the minimum tread depth for changing tires should be 3 mm. You can buy tread gauges that allow you to assess the depth of the tire tread, and you can also get more basic color-coded tools that let you know at a glance whether a tire is legal or not. Driving with worn tires means that the only area of contact between your car and the road is rather limited. This could undoubtedly lead to costly damage to the wheels or, worse, a fatal accident. Remember that the tire tread is designed to keep your tires in constant contact with the road. When your tires wear out, their ability to effectively adhere to the road decreases significantly. It also means longer braking distances and the risk of aquaplaning is getting higher and higher.
On the sidewall of your tires, you will see, among other things, a single letter. This letter refers to the speed index of your tire, or in other words, the speed at which it can be driven. Each letter from A to Z indicates the maximum speed that a tire can maintain below its recommended load capacity. There is an exception for off-road SUVs. These tires often have a lower speed rating than road tires, as they often have much more weight. In fact, one would expect most Continental tires for off-road applications to have a “Q” to “S” rating, which is about 160-180 km/h, while tires suitable for on-road use have at least a “T” rating, which is about 190 km/h. Although they have a lower speed rating, they often have a higher load index to support the extra weight of 4X4 vehicles. And of course, while your tire can run at this speed, you should never exceed legal speed limits. It is well known that the minimum legal tread depth for all passenger car tyres in Europe is 1.6 mm. Know the speed limit of your tires with the speed index Therefore, regularly check your tires, reduce your speed on wet and snowy roads and ask yourself if you need to replace your tires in time. These figures also apply to small and medium-sized SUVs or crossovers.
If you own an SUV with 4X4 features, the tread depth limits are different. Some off-road tires may start with a tread depth of 20 mm, but once worn, the tire stops working efficiently and is not safe. As you can imagine, once the shoulders and tread of an off-road tire are worn out, it will have much less traction on difficult terrain like mud, grass, and snow. Whether or not your SUV comes with 4X4 features, you know when it`s time to replace your tires with its tread wear indicators (TWI). Sometimes called wear rods, they are evenly distributed over the grooves of the tire tread. If they are at eye level with the tread, the tire should be replaced as soon as possible. Be sure to check the depth of your tread a few times a year for your own safety and security, and remember that the minimum allowed tread depth of 1.6mm is only a legal limit. For safe driving, tires must be replaced at a residual tread depth of 3 or 4 mm. Legal tire limitation: One of the most important tests of the vehicle is the tread depth of the tires. New tires start their long life on the road with a tread of 8 mm.
Although the minimum legal tire tread depth is 1.6 mm, most automotive authorities recommend changing your tires to 3 mm. Aside from the depth of the legal profile, what other important things should you keep in mind? Tyre and safety experts believe that the legal minimum of 1.6mm is not enough to ensure safety – most recommend a minimum tread depth of 3mm for changing tyres. Finally, you can do the 20p part test. Simply insert a 20p piece into the grooves of your tire`s main tread and if you can`t see the outer tread, your tire`s tread will be above the legal limit. If you can see the outer strip of the part, a tire change is likely. The tread depth of a new tyre on an SUV is practically the same as on a new car tyre – usually between 7mm and 9mm depending on the tyre model – while the legal limit in the UK for tread size is 1.6mm. The tread depth of the tire must be greater than 1.6 mm to be legal. This must be the case with three-quarters of the middle of the tire. The legal minimum tread depth for car tyres in the UK is 1.6 millimetres, on the central 3/4, which corresponds to 75% of the tread around the full circumference of the tyre. However, extensive research by ADAC has shown that the minimum legal tread depth only describes the tire`s safety margin.
For summer tyres, the remaining tread depth shall not be less than 3 mm, for winter and all-season tyres at least 4 mm. A lower tread depth can become critical on wet pavement, mud or snow. High-end tire manufacturers mold TWI into the design of the tire tread pattern. It is easy to identify; It consists of six or more small frictions on the underside of the grooves of the main profile, which are usually between 1.6 mm and 2 mm above the base of the groove. The legal limit of 1.6 mm is reached when the tire is worn at the level of the tread wear indicators in the main groove – as soon as this happens, the tire must be replaced. Book a free tire check, which is also per tire. If all four tyres are worn below the legal limit, you could lose your licence and face a fine of £10,000. If the tire is flush with them, it is below the legal limit and must be replaced. With off-road tires, you`ll notice that performance deteriorates significantly when the tread drops below 4mm, so regular users on rough terrain should consider setting a slightly higher limit on the tread depth of the tires than the normal 1.6mm. It`s per tyre, so four illegal tyres could mean a £10,000 fine and 12 penalty points.
Available tire traction is a significant safety issue on the highway, especially on wet roads. Tyre-road friction on dry and clean roads is essentially independent of tread depth and depends mainly on the nature of the road surface. However, friction between tires and wet surfaces, both for longitudinal brakes and for lateral forces in corners, depends on several variables, including water depth, tread speed and depth, and the nature of the road surface. The owner-driver of the car has control over the speed and condition of the tires, but not the depth of the water or road conditions. The minimum tire tread depth is required by law in most parts of the United States and Europe. This is not a speed reduction for wet road conditions. An overview of the government requirements regarding the legal minimum tread depth for passenger car tires in the United States is presented. Most states require a minimum profile of 2/32 inch (about 1.6 mm), but two require less, some have no requirements, and some refer to the federal criterion for commercial vehicle safety inspections. The 2/32-inch requirement is consistent with the height of tread wear bars sold in the U.S. and incorporated into passenger car tires, but the rationale for this or other existing requirements is unclear.
Recent research shows that a minimum tread depth of 2/32 inches does not prevent significant friction loss at highway speeds, even on low-wet roads. Research suggests that tires with less than 4/32 inches of tread depth can lose about 50% of the friction available under these circumstances, even before aquaplaning. It is concluded that the current requirements for the minimum tread depth of passenger car tyres are not based on rational safety considerations and that an increase in the minimum tread depth requirements would have a positive impact on road safety.