Guide to Tire Sizes: How to Read Tire Size

This post answers common questions about how to read wheel size and where to find tire sizes. 

Why are there so many tire sizes? The variety in vehicle tire sizes stems from the wide range of vehicle types, purposes, and performance requirements. Here are several key reasons why vehicles use different tire sizes and there’s no one-size-fits-all tire.

1. Vehicle type and size: Larger vehicles, SUVs and light trucks, require larger tires to support their heavier weight and larger size. Smaller cars can use smaller tires because they have less weight to support.
2. Performance requirements: High-performance vehicles may need wider tires to provide more grip and stability at higher speeds, while economy cars might prioritize smaller, narrower tires for better fuel efficiency.
3. Handling and ride comfort: The size of a tire can significantly affect a vehicle’s handling and ride comfort. Larger tires with higher sidewalls can absorb road imperfections better, offering a smoother ride, whereas lower-profile tires might provide a firmer ride but better handling and responsiveness.
4. Load carrying capacity: Vehicles designed to carry heavy loads or tow trailers require tires that can safely support the weights they haul. This often means larger and stronger tires with higher load ratings.
5. Aesthetic preferences: Some tire sizes are chosen for aesthetic reasons, with larger rims and lower-profile tires offering a more aggressive, sporty look that many consumers desire.  
6. Fuel efficiency and environmental considerations: Tire size and design can impact a vehicle’s fuel efficiency. Automakers may choose tire sizes that help reduce rolling resistance, thereby improving fuel economy and reducing environmental impact.
7. Geographical and seasonal factors: Vehicles in regions with heavy snowfall and rough terrain may need larger, more robust tires, or even specialized tires for different seasons, to ensure safety and reliability under those specific conditions.

This diversity among tire sizes allows for a more tailored driving experience, ensuring that vehicles can meet the needs of their drivers, whether it’s for day-to-day commuting, performance driving, off-road adventures, or heavy-duty hauling. The tire industry has evolved to offer a wide range of sizes and types of tires to match these varied requirements closely.

Are bigger tires better?

It depends on what “better” means to you. Bigger tires increase traction, cornering and handling, but they sacrifice other aspects of driving, and possibly fuel efficiency.

Now that you know the correct tire size for your vehicle, we suggest sticking with the recommendations. If you try to use a different tire size, it could lead to performance and safety issues.

If you have your heart set on changing sizes, maybe because you’re looking to add custom rims, your best bet is to speak with a tire professional to find a size range that works for your vehicle.

Don’t understand all the numbers on your tires? Keep reading for a quick breakdown of what the numbers indicate.

How to Find the Right Tire Size for Your Vehicle

There are a couple of easy methods to find the manufacturer’s recommended tire size for your vehicle.

Check your owner’s manual. You know that handy guide that comes with all cars that’s probably collecting dust inside your glove box? If you can’t find the manual, try the second method. Many manufacturers publish their owners’ manuals online. Look there if it’s gone from the glove box. (Actual tire placard by Honda from NHTSA.)

Check the door jamb. The second method for finding your manufacturer’s tire size recommendation is by looking at the place card inside your vehicle. You’ll find this attached inside the driver’s side door jamb, in most cases. (Sample tire placard from Bridgestone/Firestone.)

 

How to Read Tire Sizes and Wheel Size

3 ways tires are measured

Have you ever looked at the writing on your tires? There are tons of information on them that you might not understand. In this post, we focus solely on tire size. We have a related post that explains more about cracking tire codes.

There are three key pieces of information that you need to know when measuring tires. Once you understand these numbers, you can look at the tires on your car to see the size you’re currently using and make sure they meet recommendations.

One of the most common tire sizes is P 215/65 R 15. The P stands for passenger vehicle tire. You might see LT or ST instead of the P. Those stand for light truck tire and special tire.

But we’re going to focus on the numbers and what they mean. Let’s take a look at tire dimensions now.

Source: NHTSA

1. Tire width

In the P 205/65 R 15 example, the 205 means the tire is 205 millimeters wide, looking at the tire head-on.

2. Aspect ratio

The second number, 65, represents the tire’s aspect ratio. Aspect ratio indicates the tire’s height is 65% of the tire’s width. The bigger the aspect ratio, the larger the sidewall of the tire.

You can check out our extensive report on tire aspect ratio here.

3. Wheel or rim diameter

The final number of importance is 15. The 15 signifies the rim diameter of the wheel that the tire will fit. So, the rim size that you’d need is 15-inches.

Do these numbers on your vehicle’s tires match the manufacturer’s recommendations? If not, speak with a tire professional to ensure you’re driving safely. To shop for tires by size from Tire Agent, from any page, select the “SHOP BY SIZE” option, then enter your width, aspect and diameter.

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More resources to find the perfect tire

Tire size is just one factor when looking for the perfect match. There are other things to consider. Don’t worry. We’ve got you covered.

Guide to tire temperature ratings

In this guide, we explain one set of characters on your sidewalls: tire temperature grades.

Understanding tire treadwear ratings

Treadwear ratings are supposed to help us determine the value of a tire and answer questions like, how long will a tire last? And, is the tire’s expected life worth its price? Find tire tread wear info that you’re looking for.

The meaning of tire traction rating

Tire traction scores refer to a tire’s ability to stop on wet pavement. The higher the rating, the shorter the stopping distance. Check out our complete breakdown here.

_{Photo 71641465 | Tire | Alex Semenov | Dreamstime.com}