Consumer Reports on How to Decode Tire Size and Other Data

Consumer Reports doesn’t want you to be overwhelmed by all of the data on tires. While the information presented on your tires is essential, it is pretty easy to understand. Take a look at the explanations below to help decode all of the text listed on the sidewall.

How do you read tire data?

Consumer Reports on How to Decode Tire Size and Other Data
How to Decode Tire Size and Other Data | Consumer Reports

It might not seem like it at first glance, but there is a lot of information written on a single tire. Consumer Reports says that of the first pieces of information present is the tire size. That’s the part that says P235/65R17 in the above photo. The size will indicate what type of vehicle the tire should be used on, such as a regular passenger vehicle or a truck. According to Continental Tire, the P stands for Passenger tire or PMetric. A tire that says LT rather than P would identify it as a Light Truck tire.

When it comes to the numbers, the first set stands for the cross-section width in millimeters. For this tire, that is 235 millimeters. The following number is the ratio of the sidewall height to cross-section width, which is 65% in this case. The R stands for radial-ply construction. The 17 indicates how wide the tire is in inches.

In the same area, 94 stands for the load index. This indicates how much weight the tire can safely carry. You want this to be at least as high as the weight of your car. For example, you don’t want to use a passenger tire on a heavier truck.

The speed rating and treadware rating of the tire are important

Consumer Reports on How to Decode Tire Size and Other Data
Consumer Reports on How to Decode Tire Size and Other Data | Pascal Pochard-Casabianca/AFP via Getty Images

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The speed rating on a tire is indicated by a letter. The letter and its corresponding speed are listed in the chart below.

S 112 mph
T118 mph
Q99 mph
H130 mph
V149 mph
W168 mph
Y186 mph
ZR149 mph+
Speed ratings for tires

Consumer Reports says that these speed ratings might seem arbitrary, but tires with higher speed ratings tend to handle better at those speeds. “Choose tires that have a speed rating at least as high as the one specified on your vehicle’s placard.” Most cars won’t go over certain speeds regularly, so this should be easy.

When it comes to the treadwear rating, this indicates how long a tire should last. Light-duty trucks usually see numbers between 500 and 800. Consumer Reports says that, in theory, a 400-grade tire should last twice as long as one graded 200.

The traction and temperature score is pretty straightforward. These scores indicate a tire’s wet-stopping ability and temperature resistance. Traction rating AA is the best rating while C is the worst. The same goes for the temperature: A is the best score while C is the worst.

Be sure to know the manufacturing date and tire pressure

While most people know to replace tires at a certain point of tread wear, you should also replace tires after a certain amount of time. The tire used in the Consumer Reports example says DOT M6 RV THR 2321. The “2321” indicates that this tire was manufactured in the 23rd week of 2021. You don’t want to buy a tire that is too old. Six to 10 years is usually the maximum amount of time it should be used. Even if that means it was sitting in a store somewhere, the tire’s safety could be compromised.

A “max pressure X psi” rating for the maximum tire pressure will also be written in the data. This is the maximum safe air pressure for the tire. It isn’t recommended that you inflate your tires to this number, either. Generally, passenger cars are around 32 psi to 35 psi. If the number isn’t visible on the sidewall, it will be on a label in the driver’s door jamb. Consumer Reports suggests following the information on the vehicle.

All of this information is important to ensuring a vehicle is safe on the road. If you are having trouble figuring out what type of tire is right for your car, many popular tire websites have a calculator or search tool. Getting the right tires is vital to car safety, but Consumer Reports has made it easy to decide what type your car needs.

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