Whether you are buying new tires or replacing your old ones, you need to understand all the tire features and the meaning of the writings on the sidewall.
Tires speed is rated using letters A to Z; therefore, if you have Z rated tires, you have to know what it represents. What does this rating mean? Here’s all you need to know.
What Are Z Rated Tires?
Tires with a Z speed rating are ranked as the top speed a tire could achieve. Manufacturers use letters A to Z to rank tires. This speed rating ranges from 5 km/h (3mph) to above 300 km/h (186 mph). If it’s more than 240km/h (149 mph), it’s considered a Z-speed rated tire, including W & Y, used in sports cars.
For more information about Z-rated tires, why they are named this, why you need them, and what’s the difference with other tires, keep on reading!
There’s More To The Story Of Z Rated Tires
When shopping for tires, you might be confused about what the different speed ratings and codes on your tires mean. While there are different codes, what are Z-rated tires?
Tires are rated depending on the speed indicated on the sidewall and the DOT serial code.
Speed ratings are ranked by letters A to Z, with Z being the highest speed a tire could achieve.
Initially developed in Europe, the speed rating system used today was created to control the performance of tires at specific speeds.
This rating indicates the speed range in which a tire can carry a load under specified conditions.
While the speed rating ranges from 5 km/h (3mph) to above 300 km/h (186 mph), the Z rating is for speeds exceeding 240 km/h (149 mph).
However, if a tire is rated W & Y, which is 168 mph and 186 mph respectively or more, tire manufacturers will still list the tire as a “Z.”
Exotic sports cars are fitted with the W & Y tires because of their high speeds and performance levels. Therefore, you should consult your tire manufacturer if the rating is confusing.
What Does ZR Mean On The Tire Rating?
On some occasions, you’ll notice that the tire is rated ZR, which can be confusing.
When “ZR” is engraved on the size designation together with the service description, the maximum speed is what’s written on the service description.
While Z is the top speed rating, ZR may appear in the size designation for a tire with a maximum speed above 240 km/h (149 mph).
However, if the speed exceeds 300 km/h (186 mph), “ZR” must appear on the code.
Do I Need Z Rated Tires?
If you are wondering whether you need Z-rated tires for your car, here are some occasions when you should get them.
You Have A High-Performance Vehicle
If you are driving a sports car, tires with this speed rating are ideal.
However, if you have a family sedan just to run errands, it’s better to stick to other tire brands that work for your work.
Z-rated tires provide better handling for high-performance vehicles; therefore, they are worth investing in.
You Need Better Handling
If you are looking for performance tires, these Z-rated ones are the most ideal.
They might be costly because they have better handling than other tires. However, before purchasing them, weigh the benefits and downsides.
How To Identify Z Rated Tires?
Every tire has some writings on the sidewall, representing the DOT serial code, tire size, speed rating, and manufacturer’s code.
If you want to know your tire’s speed rating, you’ll need to check the sidewall. These ratings are expressed in letters and listed along with the load index and tire size.
It’s easy to identify because it’s the last letter on the tire’s size code.
For instance, if the code is P245/40R18 93Z, 93 is the load index, and the “Z” is the speed rating. This load index and speed rating are known as the service description.
You can find your tire speed rating either on the owner’s manual, glove box, driver’s side doorjamb, gas tank hatch, or any other location with your tire code.
How Are Speed Ratings Determined?
Tire manufacturers determine the speed rating by testing according to the Economic Commission for Europe (ECE) standards and regulations.
They are determined using laboratory testing using simulated speeds and loads. Therefore, the tires must reach a specific speed according to industry standards.
For these tests, the tire is inflated and mounted on a testing machine. Tire professionals then press the tire against a metal drum to simulate a load and then spin the tire for 10 minutes at the target speed.
If the tire doesn’t separate the tread components or experience any failure, this number is passed as the speed rating. Therefore, tires with higher speeds are rated Z.
Keep in mind that the tire’s speed rating indicates the capabilities under a controlled environment.
Therefore, the vehicle’s condition, inflation, wear and tear, driving conditions, and alignment could affect the actual speed rating.
Therefore, these ratings don’t apply if the tires are not properly inflated, damaged, or overloaded.
If you are looking to learn more, you can also see our posts on what are D-rated tires, what are MT tires, and what are OEM tires.
Summary
Z-rated tires are the highest speed a tire could achieve; therefore, they are mostly used in performance vehicles.
If the speed rating is above 240km/h (149 mph), it’s considered a Z-speed rated tire, including W & Y ratings that are at 168 mph and 186 mph, respectively.
You should consider getting these tires if you have a sports car because they have better handling at high speeds.
