Tire Speed Ratings, Traction, and Tread Life and Why It Matters
When it comes to buying new tires, some drivers race to find the right size at the best price. Those are not bad qualities to search for. But there is more to a tire than its size – or the size of its price tag. In fact, a tire sports more than a dozen different qualities, including how it performs in wet or slippery conditions and how it holds up in the heat. Some of these qualities can and should impact your buying decision.
Of course, tire size is important to ensure the best performance from your tires. After all, vehicle manufacturers engineer the steering, suspension, and brake systems to work with tires of a certain size, or at least within a given size range. But once you have identified the proper size – the width, aspect ratio, and rim diameter – other qualities rise in significance. Depending on the type of vehicle you drive, three characteristics in particular pop out. If you want to choose the right tires for your car, you should also consider their speed, traction, and tread life ratings.
Why is Tread Life Important?
Let’s start with tread life first, since many tire shoppers care very much about how long their tires last. Over time, your tires will wear down and their tread depth will diminish. Regular tire rotation and proper wheel alignment serve to make your tires last longer. But eventually they will wear out.
Tread life, also referred to as “treadwear,” indicates a rating that compares a new tire against an industry standard. A rating of “100” represents the standard for the length of time tire tread lasts. If a tire is rated at “200”, the tire should be capable of lasting twice as long as the industry standard. “400” would last four times as long, and so forth. The treadwear rating, along with a lot of other information, is embossed in code on the side of a tire.
Unfortunately, treadwear ratings are more like estimates than actual measurements. And they do not correspond to actual miles driven. They are simply a measurement against a standard score. Treadwear ratings are not especially helpful when comparing tires of one brand against those of another.
Treadwear warranties offered by tire manufacturers are another measure to consider when buying tires. They might suggest that a particular tire can last, say, 50K or 60K miles. But again, warranties are none too helpful when comparing different brands head to head. This is mostly because warranty numbers, like treadwear ratings, are self-reported by the manufacturers.
Both treadwear and warranty ratings are best considered when comparing a tire of one brand against another tire of the same brand. So, a model rated at 400 from Brand X should last longer than one with a 200 rating from Brand X. Or a tire with a 70K mile warranty from Brand Y should provide more mileage than one with a 50K mile warranty from Brand Y.
In any case, higher treadwear ratings and warranties, while not necessarily a guarantee that your tires will last any specific number of miles, can be a helpful piece of evidence when comparing tires within a brand.
Why is Tire Traction Important?
Your tires are the most important safety feature of your vehicle. If your tires do not have adequate tread left, your car will not handle the way it should. It will not grip the road when you accelerate. It will not corner as it should when you turn. And it will not stop in a reasonable amount of space when you brake.
Naturally, if your tire tread is worn down too much, your old tires will have a hard time gripping the road (and might even hydroplane when you drive over wet surfaces). But did you know that some new tires grip better than others? Not all tires perform the same; different models of tires offer different levels of traction.
So, tires also have a traction rating. This rating denotes a tire’s ability to maintain traction during straight-line braking on a wet surface. Traction is graded from “AA” at the high end, to “C” at the low. The higher the ranking, the better the traction. A majority of tires on the road (about seventy-five percent) are rated an “A”. Slightly more than twenty percent score a “B”. Only a small percentage are ranked with the highest marks – or the lowest.
There is usually a trade-off between treadwear and traction. The better the traction, the shorter the tread life, and vise versa. The all-popular all-season tire is an example of a balance between the two.
Why is the Tire Speed Rating Important?
The speed rating on a tire tells you of its ability to maintain a certain speed over time. While tire makers set their own speed ratings, the Department of Transportation sets the scale. A higher rating means that your tire should have better handling ability and control at higher speeds. A high rating also means that a tire should be able to handle more heat.
The rating system uses a set of letters that correspond with speeds. For instance, S (at 112 mph) and T (118 mph) are ratings commonly found on sedans, minivans, and light trucks. V, W, And Y (rated from 149-186 mph) are used on many high-performance cars. Others are used on trucks. For the most part, the higher the letter in the alphabet, the higher the speed rating, with the exception of the letter H, designated for the higher speed of 130 mph back when there were only three ratings total.
So, why is speed rating important? Well, when you are shopping for tires, you should only pick those that have a speed rating that, at minimum, matches what your vehicle manufacturer recommends. You can opt for a tire with a higher rating – they will perform just fine at slower speeds – just do not choose a lower rating. After all, it does not matter if you are driving a sports car or a minivan, secure handling is still of utmost value. The only real downside to moving up on the speed rating chart (other than potential cost) is that tires with higher speed ratings wear faster than those lower on the list.
When you are looking for new tires, go ahead and hunt for a bargain. But also make it a priority to purchase the right tires with the right ratings for your car.
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