It's needless to say that your car's tyres are a very important part of travelling safely. This quick lesson in tyre basics will help you better understand the rubber that your car rolls on.
What do these numbers mean?
As pictured above, the numbers here relate to the sizing of the tyre as well as speed rating. Let’s break it down.
205 – Relates to the width of the tyre. This is measured in mm.
50 – Relates to the profile which means how high the sidewall of the tyre is as a percentage of the section width mentioned above. This is measured in mm.
R17- Is the diameter of the tyre measured in inches. The letter ‘R’ means the tyre’s construction, which means ‘Radial’. Pretty much all new car tyres are radial construction.
89H- The number ’89’ refers to load rating. Load rating is basically a grading that tells you how much weight a tyre can take. Remember, along with managing grip, a tyre also has to manage the weight of a vehicle. Naturally, all 4 tyres on a car will share that total weight. The letter, in this instance ‘H’ refers to the speed rating. ‘H’ pictured here means that this tyre is rated for 210km/h. Different letters mean different speeds.
Let’s take note of the above picture. In a general instance, you don’t need to worry too much about treadwear, traction, and temperature. It’s worth noting the numbers and letters here aren’t standardised across the board and differ from brand to brand. These figures and ratings here particularly relate to how the tyre performs within its brand’s range.
Treadwear refers to how soft or hard the tyre compound is. Basically, the softer the tyre, the grippier it can be but also wears faster. The harder the tyre, they can last longer but have admittedly less grip.
Traction is the grading for how well a tyre will stop in wet conditions. It’s tied to stopping distance.
Temperature is the tyre’s resistance to generating heat at speed. Some heat is fine but you don’t want too much heat as it can affect wear.
Tread wear indicators
One of the ways you can tell your tyres are wearing down is by looking at the tread wear indicators. This is an easy way to tell if your tyres are about to finish and you’re due for replacement. There are markers around the tyre sidewall indicating where the treadwear strips are. The treadwear strips are sunken below the tread blocks. When the tread blocks wear down and are in line with the wear indicator strips, that shows your tyres have finished and are due for replacement. Generally, your tyre tread will wear evenly but if you don’t put in the correct air pressures, your tyres will wear unevenly. The minimum legal limit for tread depth in South Africa is 1.6mm. If you’re rolling around on tyres with such low tread depth, and an accident occurs, your insurance may not payout. So keep an eye on those treads.
Tyres begin to lose their functionality and grip as they wear down as well as age. You’ll especially notice this in the rain.
So check your tyres regularly and don’t forget to keep your air pressures appropriately topped up as this also affects how your tyres wear.
What’s right for your car?
You’re probably wondering, “What is right for my car?” This information is pretty easy to source. For one, your owner’s manual will bless you with such information (especially in a pinch.) If your owner’s manual isn’t with you, then there’s generally a sticker on the driver’s side door that will give the tyre sizes and pressures for different loads. When you need to replace your tyres, sometimes you can get away with minor changes in sizing but they can potentially affect a few driving dynamics of your vehicle. Ideally, try to get the same size tyres that are recommended by your manufacturer as these are tried, trusted, and researched.
Tayedza MbiriStarting his petrol-infused passion at a ripe young age playing a plethora of racing video games, Taye has been into the motoring industry for years. During his university years studying Law, he dipped his toes into motoring photography, videography, and exploring what Southern Africa has to offer for the motoring scene at large. Most recently, he presented a YouTube series for a famous Japanese manufacturer and now finds himself fresh on the AutoTrader content creation team. He hopes to own a 90s Subaru one day soon. View News & Reviews