Tire Sizes and Ratings: A Guide to Choosing the Right Tires

Just like your feet need new shoes, your vehicle will eventually need new tires at some point - even with regular rotations. And just like shoes, tires are not one-size-fits-all components. Different vehicles require different types of tires to provide a safe, smooth, and efficient ride.

In this post, we'll explain tire sizes and ratings to help you choose the right tires the next time you're in the market for them. Read on to learn more or contact your local GreatWater-affiliated shop for more information.

What Do Tire Sizes Mean?

As we said, tires are not one-size-fits-all components. To ensure you're purchasing the right tires for your vehicle, it's important to select the right size.

How to Read Tire Sizes

Looking to understand what types of tires your vehicle needs? One way is to reference the vehicle operator's manual, but the easier way is to simply check your current tires' sidewall. There, you'll find a combination of letters and numbers, a sequence that can help you understand your tire type, tire width, aspect ratio, construction, wheel diameter, load index, speed rating, and flotation sizing.

Tire Type

Tire type is determined by the first letter in the sequence. Often, this is a "P," which signifies a tire for a passenger car. If there is no letter to start the sequence, it's often indicative of the Euro metric for a passenger vehicle.

Tire Width

The first numbers in the sequence identify the tire width your vehicle requires. Width is measured from sidewall to sidewall. For instance, if the number is "225," then you need tires with a width of 225.

Aspect Ratio

The next number in the sequence is the aspect ratio, or how tall the tire profile is. For instance, if the sequence starts "P225/75," then the aspect ratio is 75.

Construction

Construction is indicative of the letter after aspect ratio. It's often "R," radial, "B," bias ply, or "D," diagonal. For a sequence of "P225/75R," the construction would be radial.

Wheel Diameter

Wheel or radial diameter is the next number following the construction letter.

Load Index

Load index is the next number, which indicates how much weight the tire can support when properly inflated. Make sure to reference a load index chart based on the number. For instance, a sequence of "P225/75R1685" has a load sequence of 85, which can support 1,135 pounds when properly inflated.

Speed Rating

Speed rating is the final letter in the sequence, often an "R" or an "S." "S" is rated for higher speeds, while "R" is rated for lower speeds.

Flotation Sizing

Flotation sizing is common for aftermarket tires for an off-road vehicle. They also have different sequences, which indicate overall diameter, section width, construction, rim diameter, LT type, load index and speed rating, and quality grading.

In The Market for New Tires? Find a Locally Managed GreatWater-Affiliated Shop Near You!

For more information on tire sizes and tire comparison between different types of tires and for tire alignment and maintenance, contact your nearest shop in the GreatWater network today.