How to Read Tire Size: Your Sidewall Numbers Explained

You look at the side of your tire and see something like P215/65R16 98H. It looks like a serial number from another dimension. Letters, slashes, numbers, what does any of it actually mean?

Here’s the thing: it’s not random at all. Every part of that code tells you something specific about the tire. Its width, height, what kind of wheel it fits, how much weight it can handle, and how fast it’s rated to go. Once you break it down piece by piece, it becomes pretty intuitive. And knowing this stuff puts you in a much better position when you’re shopping for tires, so you’re not just trusting whatever someone hands you.

Need the right tires for your car right now? Check out our tire installation page or call us directly. We’ll match you up fast and make sure you get the right fitment for your vehicle.

Where to Find Your Tire Size

Before decoding anything, you need to find the number. There are two easy places to look:

1. The tire sidewall: Look at the outer edge of any tire on your car. The size is molded directly into the rubber in large, bold text. You can’t miss it once you know where to look.
2. The driver’s door jamb: Open your driver’s door and check the sticker on the inside of the door frame. It shows the manufacturer-recommended tire size for your specific vehicle, along with recommended inflation pressure.

The door jamb sticker is actually the more reliable reference when buying replacement tires. It tells you exactly what size your car was engineered for, not just what was mounted when you bought it.

You can also find your tire size in:

• Your owner’s manual (usually in the maintenance or specifications section)
• The glove box sticker on some vehicles
• Online via your vehicle’s year, make, and model if you don’t have access to any of the above

What Each Number and Letter Means

Let’s decode P215/65R16 98H piece by piece. Here’s the full breakdown at a glance:

Width, Aspect Ratio & Rim Diameter

Breaking each one down:

• “P” stands for passenger vehicle. You might also see “LT” (light truck), “ST” (special trailer), or no prefix at all. That’s a Euro-metric tire, common on European cars. The prefix sets the context for how the rest of the numbers should be interpreted.
• “215” is the tire’s section width in millimeters, measured from sidewall to sidewall at the widest point. A wider tire generally provides a larger contact patch, which can improve grip but also increases rolling resistance slightly.
• “65” is the aspect ratio. The sidewall height expressed as a percentage of the width. So 65% of 215mm gives you roughly 140mm of sidewall. Lower numbers like 45 or 35 give you a low-profile, sporty look and sharper handling. Higher numbers like 65 or 70 mean a taller sidewall, more cushion, and a smoother ride on rougher roads.
• “R” stands for radial construction, which describes how the internal cords inside the tire are layered. Radial is the standard for virtually all modern tires. You’ll rarely see anything else.
• “16” is the wheel diameter in inches. This number must match your wheels exactly. There’s no wiggle room here, a 16″ tire on a 17″ wheel simply won’t work.

Load Index & Speed Rating

Here is the breakdown for the load index and speed rating written in clear bullet points:

• 98 (Load index)
  • What it means: The maximum weight capacity each tire can safely carry.
  • In this example: A rating of 98 translates to a capacity of 1,653 lbs per tire.
• H (Speed rating)
  • What it means: The maximum sustained speed the tire can safely handle under its recommended load.
  • In this example: An H rating certifies the tire for speeds up to 130 mph.

Pro Tip: When replacing tires, you should always match or exceed the load index and speed rating specified by your vehicle’s manufacturer. Installing a tire with a lower capability can compromise your handling and safety.

Load index quick reference:

Speed rating quick reference:

For everyday driving, you don’t need to obsess over speed ratings. Just match or exceed what the factory specifies, never go lower. Going lower means the tire isn’t rated for the stresses your vehicle puts on it, which is a safety issue over time.

A Real Example, Decoded

Let’s put it all together. Here’s P215/65R16 98H fully broken down in one table:

This is a very common size. You’d see it on something like a Toyota Camry, Honda CR-V, or similar mid-size vehicle. Nothing exotic, just a solid, practical all-season setup that millions of cars run. If your car has this size on it now, replacements are widely available and typically very affordable.

How to Use This When Buying Tires

Now that you can read the code, here’s how to actually apply it when shopping for tires:

Step 1: Find your current size.
Check your tire sidewall or door jamb sticker. Take a photo with your phone so you don’t forget it when you’re at the shop or shopping online.

Step 2: Match the critical numbers.
When replacing tires, the rim diameter must match exactly. Always. Width and aspect ratio should stay close to factory specs too. Changing these numbers can affect your speedometer accuracy, how the tire sits in the wheel well, and overall handling behavior.

Step 3: Never downgrade load index or speed rating.
These are safety specifications. They tell you how much stress the tire is designed to handle. Always match or exceed the factory recommendation, never drop below it.

Step 4: Factor in your driving conditions.
The code tells you what size you need, but not which specific tire is right for your lifestyle.

• Mostly highway miles? A touring tire might suit you better.
• Colorado winters with mountain driving? All-season or dedicated winter tires are worth the investment.
• Hauling heavy loads regularly? Look for a higher load index.

For more context on tire wear and when it’s time to shop, check out How Long Do Tires Last.

FAQs

How do I find my tire size?
Check the sidewall of any tire on your car, or the sticker on the inside of your driver’s door jamb. Both give the same information. The door jamb is the most reliable source for your factory-recommended size.

Can I use a different size than what’s on my car now?
Small variations are possible with proper guidance, but the rim diameter must always match exactly. Stick with the factory size when in doubt, and talk to a tire professional before making any size changes.

What does the “R” in tire size mean?
Radial. It describes how the internal cords are layered inside the tire. Almost all modern tires are radial construction, so you’ll see R on virtually every tire you look at.

What happens if I use the wrong load index?
You risk tire failure, especially when the vehicle is loaded with passengers or cargo. The tire simply isn’t engineered to handle the stress. Always match or exceed the recommended load index.

What’s the difference between load index and load range?
Load index is used on passenger tires and is expressed as a number. Load range (shown as a letter like C, D, or E) is used on light truck tires. Different rating systems, same core idea, how much weight the tire can safely carry.

Does tire size affect fuel economy?
Yes. Wider tires create more rolling resistance, which can slightly reduce fuel efficiency. Sticking close to the factory size generally gives you the best balance of efficiency, handling, and comfort.

Need Help Choosing Tires? Ask All Season Auto Tire

Don’t want to decode all of this yourself? Totally fair — it’s what we’re here for. Bring your car in or give us a call and we’ll match you with the right tires for your vehicle, driving style, and budget. No guesswork, no upsells on sizes you don’t need.

At All Season Tire, we offer professional tire installation in Englewood, CO with same-day service and competitive pricing on both new and used tires.

Not sure which size you need? We’ll help. Contact us or call 720-877-4243