Depending on where you live in the world, you should be mindful of several important SUV tire figures – not only because they’re often legal requirements, but because they will help extend the life of your tires and also support your driving safety.
The key aspects you need to watch out for in all car tires are age, tread depth, maximum speed and load index. Let’s take a closer look at the requirements.
You may already know that the legal limit for tread depth on regular road tires is 1.6 mm. However, our tire experts strongly recommend having a minimum tread depth of 3 mm for regular summer road tires and 4 mm for regular winter road tires. These figures also apply to small to medium SUVs or crossovers. Although the difference between 1.6 mm and 3 mm is only about the equivalent of two credit cards pressed together, these millimeters make meters of difference when you suddenly need to break – particularly in wet weather conditions.
If you own an SUV with 4X4 capabilities, the limitations for tread depth are different. Some off-road tires may begin with 20 mm of tread depth but once they get worn down to 5-6 mm, the tire will stop working effectively and will be unsafe. As you can imagine, once the shoulders and tread of a off-road tire get worn down, it will have far less traction on tough terrains like mud, grass and snow. Whether your SUV has 4X4 capabilities or not, you will know when it’s time to replace your tires by its tread wear indicators (TWI). Sometimes known as wear bars, they are evenly spaced throughout the grooves of the tire tread. If they are level with the tread, the tire must be replaced as soon as possible.
On the sidewall of your tires, amongst other figures, you will see a single letter. This letter refers to your tire’s speed rating index, or in other words, how fast it can be driven. Each letter ranging from A-Z denotes the maximum speed a tire can sustain under its recommended load capacity.
For off-road SUVs, there’s an exception. These tires will often have a lower speed index rating compared to on-road tires because they often carry a lot more weight. In fact, you could expect most Continental tires for off-road usages to have a “Q” to “S” rating, which is about 160-180km/h, while tires suited for on-road usage have at least a “T” rating, which is about 190 km/h. Although they have a lower speed index, they often have a higher load index to carry the additional weight of 4X4 vehicles. And of course, while your tire can perform at this speed, you should never exceed legal speed limits.
While most off-road SUVs lack in speed when compared to sedans, the tires they are typically equipped with have a much higher load index. The load index is the maximum capacity a tire can carry. And as you might have guessed, the higher the load index number, the greater the tire's load-carrying capacity. This is especially important when you need to tow a trailer. It is also vital to note that the load index rating represents the load-carrying capacity of tires inflated to maximum tire pressure; this means the load-carrying capacity will go down as tire pressure is reduced. You can learn more about SUV tire pressure here.
If you have a small-medium SUV that is purely used for on-road purposes, the same rule applies. You can also find the full details about your maximum tire load index in your vehicle’s manufacturer’s manual. If you’re ever in doubt, visit your local tire specialist.
On-road or highway tires, including those for crossover SUVs, should be replaced at least every 10 years – including the spare. This upper age limit applies if they have been properly looked after with routine checks, have no damage and the tread meets the minimum depth requirements. We suggest replacing off-road SUV tires at least every five years if they're used frequently in off-road conditions, or to have them checked every year once they reach the five-year mark. Off-road SUV tires don’t last as long as regular vehicle tires, because the tread gets worn down much faster with the weight of the vehicle and the tough terrain it crosses. You can learn more about replacing your SUV tires here.