Have you seen a whole slew of characters and numbers that includes information about size, construction, and guidelines for use of the tire? Those are the tire ratings and let us here on Online Wheels Direct help you decipher them and know why it is important to understand them.
Now, what does a tire’s loading rating index mean? This determines how many pounds a tire can safely carry. How much weight can your tires carry? First, look for the load index written usually on the door jamb placard then multiply the pounds by 4. Compare it to the Gross Vehicle Weight Rating. As long as the latter is less than the load index multiplied by 4, you’re good to go. Let’s take as an example, an Audi that has been assigned to a load carrying capacity of 1477 pounds (per tire). Say the Gross Vehicle Weight Rating of an Audi which includes the car itself, the driver, passengers, dog, and dog food is 4597 lbs. We want it to be safe by making sure that the weight of the car combined with the weight of the cargo wouldn’t exceed 5908lbs. (1407 x 4). Since the combined load rating (5908 pounds) for the four tires are greater than its GVWR, then it should be fine.
Next thing to know is how tires are rated for speed. A speed rating is an indication of the tire's maximum speed capability in ideal conditions which is set by the tire manufacturers and based on testing. The tire speed rating is expressed as a letter adjacent to the tire's load index and these are as follows:
H speed rating tells you that your tire is approved up to 130mph (210 km/h) under optimal conditions. These are ideal for sport and luxury coupes and sedans as they are common in the grand touring all-season tire category. What goes hand in hand with this tire are those V speed rating ones that approve up to 149mph (240km/h). Its performance attributes are often associated with high speed and high-performance tires.
T speed rating approves up to 118mph (190km/h). This is commonly fitted to family sedans and minivans or in any everyday passenger vehicles.
W speed rating approves up to 168mph (270km/h). These tires land firmly at the performance end of the tire speed rating spectrum. It is also known to fall under the ultra-high performance all season tire category, making it suitable for street driven exotic sports cars.
Y speed rating can go up to 186mph (300km/h).
Z speed rating indicates speed up to 149+ mph (240+ km/h). This is ideal for performance coupes and sedans, sports cars, and supercars.
P speed rating approves up to 93 mph (150 km/h).
Q speed rating approves up to 99mph (160km/h). Studdable and studdless winter tires are examples of this.
R speed rating allows up to 106mph (170km/h). These are rare but can be found on some heavy duty light truck (LT) tires.
S speed rating approves up to 112mph (180 km/h). Some all-terrain LT vehicles are now becoming available in S speed rating.
M speed rating indicates that tires can go up to 87mph (140 km/h) while N allows 81 mph (130 km/h). You’ll find both on spare tires.
You might be wondering if you can mix different speed rating of tires on your vehicle. It is better if you do not mount different speed rating in one vehicle. However, if you can’t avoid that, you have to put the lower speed-rated tires on the front axle in order to avoid oversteering which can affect the handling of the vehicle. When you do this, it can also affect the speed capacity of the vehicle because of the low speed-rating tires are in front. If you want to maximize the speed potential and performance of the vehicle, you must install a uniform size and speed rating of tire set.
Don’t be assured that if your tires can perform up to 130 mph, that doesn’t mean you should drive 130 mph. It means the Audi A3 is capable of a top speed of 130 mph. It’s still generally a good idea to observe these speed limits. Aside from cheap wheel and tire packages available in our online wheels store, our first consideration is the safety of our Customers.