Tire – Page 10 – Rx Mechanic

The speed rating for any given tire is the optimal speed at which it can safely carry a load for a sustained period in ideal conditions. The load consists of the original weight of the vehicle plus whatever it’s carrying. The tire speed rating was developed in Europe in the 1960s. It was developed to help control the safe performance of tires at standardized speeds. When the tire speed rating chart was first developed, only three existed: S, H, and V. As tire technology further developed, they added new speed ratings such as R, M, U, and others. The rating is usually signified by a letter or two. Every letter is represented in a standard tire speed rating chart. Generally, in all ratings except Unlimited ZR, the rating is usually molded on the tire's sidewall. It is usually after the tire load index. The load index is associated with the maximum load the tire can carry when well-inflated. The tire load index, together with the speed rating, make up the service description. You can also find the tire description in the glove box door, owner’s manual, gas tank hatch, and driver’s side doorjamb. Tire Description It is also known as a Service description. Most of the information you need to know about a tire is found on the sidewall. The information generally consists of numbers and letters molded into the rubber. These numbers and letters tell very important details about the characteristics of your tire. An example of a tire description is 215/65R 15 95H TIRE DESCRIPTION 215/65R 15 95H 215- Section Width in Millimeters 65- Aspect Ration R- Radial Construction 15- Rim diameter in Inches 95- Load Index Service Description H- Speed Symbol ZR Designation ZR is a speed rating for tires with a maximum speed capability higher than 149mph. ZR tires include the tire speed rating V, W, and Y. V means that vehicles can safely use the tire with a top speed higher than 149mph. The rating W shows that the tire is safe to use for a vehicle with a top speed of 168mph. The speed rating Y shows that the tire is ideal for a vehicle with a top speed of 186mph. ZR DESIGNATION EXAMPLES Tire Designation Maximum Speed 205/45R17 88W 270km/h (168mph) 205/45R17 88Y 300km/h (186mph) Tire Speed Rating chart This chart includes alphabets that indicate the speed rating for tires. The higher the alphabet a tire is rated, the better it will manage heat and faster speeds. However, H is an exception. It was decided to keep the H-speed rating at 130 mph as an exception to manage the older tires in the market. Many drivers tend to drive within the limitations of the tire speed rating H. Below are the symbols and translation into mph TIRE SPEED CAPABILITIES SPEED SYMBOLS Symbol Speed Speed (km/h) Speed (mph) A1 5 3 A2 10 6 A3 15 9 A4 20 12 A5 25 16 A6 30 19 A8 40 25 B 50 31 C 60 37 D 65 40 E 70 43 F 80 50 G 90 56 J 100 62 K 110 68 L 120 75 M 130 81 N 140 87 P 150 94 Q 160 100 R 170 106 S 180 112 T 190 118 U 200 124 H 210 130 V 240 149 W 270 168 Y 300 186 FAQs What Is a Good Speed Rating for Tires? A good speed rating for your tires is at least that which your car’s manufacturer recommends. You can move up to a higher-rated tire but not lower. Many drivers tend to use tires within the H limitations. When using the truck tire speed rating charts, it is safe to go with N-H-rated tires for light trucks. You can choose to use ZR-designated tires if you have a high-performance car. Speed Ratings S, L, T, U, and H are some of the best speed ratings. What Is H Or T Rating On Tires? A tire speed rating of T shows that you can safely drive it up to 118mh. On the other hand, a speed rating of H indicates that the tire can be safely used up to 130mph. You should not mistake this with the H/T on tires. This stands for highway/terrain. Such tires are designed for vehicles driven primarily on highways, but you will also use that at times off-road. Trucks and SUVs most commonly use H/T tires. These tires are made for paved roads. Does the Speed Rating on a Tire Make a Difference? The speed rating on a tire makes a great difference. A tire with a higher rating offers better handling to the driver. Higher speed-rated tires also offer better grip and stoppage power. However, they have a short tread life and low performance in cold conditions. Tires with low-speed rates tend to squirm under pressure. Consequently, they cause heat build-up. This compromises traction and treads life. Despite this, low-speed-rated tires have a good performance in cold conditions. Why Are Run Flat Tires Bad? Run-flat tires reduce the overall tread wear. Moreover, they are more expensive to replace. They usually affect the ride experience, making it harsh or rather noisy. Most cars equipped with run-flats do not carry a spare wheel and tire. Even if there is a spare in the car, run-flat tires are hard to fix. They also have low availability. This is because most run-flat tire models are made for new vehicles rather than for replacement. Should I Get H Or V Rated Tires? Generally, both V and H-rated tires are considered to be performance-touring tires. Whichever you choose may come down to how fast you intend to go. For a high-speed, V-rated cars are great. They offer a firmer ride and better handling compared to H-rated tires. Moreover, they have a stiffer sidewall. H-rated tires provide a comfortable ride during normal driving conditions. Other than speed, these tires cost less and usually last more miles. H-rated tires have less rolling resistance, thus better gas mileage. Can I Mix V And W Rated Tires? Many manufacturers advise against using tires with different speed ratings. The main reason is that mixing reduces the maximum safe speed. For your own well-being, I’d not recommend this. When you mix V and W-rated tires, you will have problems with handling your vehicle. It is only safe to match the speed rating of your tires across the axle. Can I Put a Higher Speed Rated Tire on My Car? It is always advisable to use the speed-rated tire your manufacturer recommends. However, installing higher-speed-rated tires in your vehicle is allowed. With higher-speed-rated tires, you can drive faster. Notwithstanding, they do not improve the cornering ability or increase tread wear. Does Tire Speed Rating Affect Ride? Your tire’s speed rating has a huge impact on your driving experience. It is not only about how fast you drive. It also affects your cornering abilities, your wear, and your comfort. Generally, higher speed-rated tires offer better grip and handling, hence better comfort. Final Words: Always remember that a tire’s speed rating is not just about speed. It also includes performance. Performance usually involves how your tires get rid of heat and how they brake, grip, corner, and swerve. It is advised to choose the speed-rated tire recommended by the manufacturer. Avoid mixing tires with different speed ratings. If you choose to mix them, mount the lower-speed rated tires on the front axle. You can always install higher-rated tires on your ride. The only time you can downgrade is in very cold temperatures, such as winter. Q-rated tires are the best to use in winter. A tire’s true capability is not only determined by the tire speed rating. This is because the Tire Speed rating is based on laboratory simulations. Choose a tire with a speed rating that works best for you. Maintenance is also important in improving the tire’s tread life. Finally, you should always obey legal limits despite your tire speed rating.