What size are my truck tires?

Your truck tire size is printed on the tire sidewall and on the vehicle’s door placard; use that information to match the width, profile, and rim diameter when replacing tires.

Understanding tire size matters for safety, performance, and accuracy of your speedometer. This article breaks down where to find the size, how to read the format, and what to consider when replacing or upgrading tires on a truck.

Where to Find Your Tire Size

Start with the most common sources: the tire sidewall, the driver’s door jamb placard, and the owner’s manual. The sidewall shows the exact size of the tire currently mounted, while the placard lists the recommended original equipment size and inflation pressures for your vehicle. The manual can confirm specifications and provide guidance if you’re contemplating a different size for performance, clearance, or load considerations.

• Tire sidewall markings show a size code such as P265/70R17 or LT275/65R18, plus additional load and speed information.


• Driver-side door jamb placard provides the original tire size, recommended cold inflation pressure, and sometimes load ratings for front and rear.


• Owner’s manual may list compatible sizes and any manufacturer-approved alternatives for different trim levels or regional markets.


• VIN-based build sheets or dealership records can confirm the tires originally equipped by the factory, which is useful if you’ve traded tires before and aren’t sure of the current size.

When in doubt, verify with your vehicle’s manufacturer recommendations or a trusted tire professional to ensure the size you choose fits the wheels, suspension, and clearance requirements.

Understanding the Tire Size Format

Tire sizes use a standardized code that encodes width, height, construction, and wheel diameter, along with optional load and speed ratings. Here’s how to interpret a common format.

Components of the size code

Each segment of the code communicates a specific measurement or spec. Below are the elements you’re most likely to see on a truck tire.

• P vs LT vs C: P indicates passenger-car sizing, LT indicates light-truck with higher load capacity, and C is commercial; trucks and heavy-duty pickups often use LT or C.


• Width (in millimeters): the first number, e.g., 265, 275, or 315, describes the tire’s cross-sectional width.


• Aspect ratio: the second number (percentage) expresses the tire’s height as a percentage of its width, e.g., 70 or 65.


• Construction: the letter R stands for radial construction (most modern tires); D would indicate diagonal construction, which is rare on modern trucks.


• Rim diameter: the final number in inches (e.g., 17, 18, 20) indicates the wheel diameter the tire is designed to fit.


• Load index and speed rating (optional): a following pair like 113S indicates load-carrying capacity (113) and maximum speed (S); higher numbers/Ratings denote greater capability.

Understanding these components helps you compare tires accurately and ensures you buy a size that matches your vehicle’s requirements and your driving needs.

Common Truck Tire Size Scenarios

Truck owners encounter a few typical formats, each with its own implications for fitment and performance. The following examples illustrate common layouts you might encounter on pickups, SUVs, and work trucks.

• P245/75R16: A common light-truck or SUV size with a 16-inch wheel, balanced for everyday use.


• P265/70R17: A popular all-purpose size for many mid-size pickups and SUVs, offering a balance of comfort and load capacity.


• LT275/65R18: A heavy-duty light-truck size with higher load capacity, often used on pickups or vans with tougher hauling needs.


• 33x12.50R17: A metric-style designation converted to inches that describes overall tire diameter (roughly 33 inches) and width; frequently used on lifted trucks.


• LT33/12.50R20: A large, rugged LT-size tire designed for heavy-duty use with a 20-inch wheel; common on newer, larger trucks with aggressive setups.

When selecting a replacement, aim to match or carefully exceed the original diameter within manufacturer guidance. A mismatch can affect speedometer accuracy, traction, and gearing behavior.

What to Do When You’re Upgrading or Replacing Tires

Replacing tires isn’t just about matching numbers. You must consider clearance, load, and overall performance. The following steps help ensure you choose a compliant and safe option for your truck.

• Start with the original equipment size from the placard or manual; use it as your baseline for replacements.


• If upgrading to a larger size, keep the overall diameter within the range recommended by the manufacturer, and be mindful of potential speedometer and gearing changes.


• Check for sufficient clearance in wheel wells, fenders, and suspension components, especially if you’ve installed a lift or altered ride height.


• Ensure the chosen tires have an appropriate load index and speed rating that meet or exceed your vehicle’s requirements.


• Confirm wheel width and offset compatibility with the new tire size to avoid rubbing or improper seating on the rims.


• Verify that the spare tire also matches or is compatible with the rest of the tires on the vehicle.

Proper planning and verification help maintain safe handling, braking performance, and compliance with regulations for your specific truck model.

Summary

In short, your truck’s tire size is encoded on the sidewall and listed on the door placard, and sometimes in the owner’s manual. Learn to read the size format (for example, LT275/65R18 or 33x12.50R20), understand what each segment means, and follow manufacturer guidance when replacing or upgrading tires. Always verify fitment, load rating, and clearance, and consult a tire professional if you’re unsure.

By knowing where to look, how to read the code, and what to check before buying, you can maintain safe performance and proper fitment for your truck’s tires.

What does 4.80 4.00 mean?

The numbers 4.80/4.00-8 read like this: 4.80" is the tire width, 4.00" is the tire section height (from the inside of the donut hole to the outside) and the 8" is the wheel diameter. Finally, the numbers 4.80-8 read like this: 4.80" is the tire width and "8 is the wheel diameter.

How do I tell what size my truck tires are?

To read a truck tire size, decode the alphanumeric code on the sidewall, which typically includes the tire's width in millimeters, the aspect ratio (sidewall height as a percentage of width), the construction type (R for radial), and the rim diameter in inches. For example, in 295/75R22.5, 295 is the width, 75 is the aspect ratio, R is radial construction, and 22.5 is the rim diameter. Some sizes, like those for flotation or LT tires, may use a different system that directly specifies height, width, and rim size in inches.
 
Metric tire size (e.g., 295/75R22.5) 
This video explains how to read a metric tire size: 50sAutoWebYouTube · Jun 11, 2013

• Width: The first number (e.g., 295295295) is the tire's width in millimeters from sidewall to sidewall. 
• Aspect Ratio: The second number (e.g., 757575) is the sidewall height as a percentage of the width. 
• Construction Type: The letter (Rcap R𝑅) indicates the tire's construction. 'R' stands for radial, which is the most common type. 
• Rim Diameter: The final number (e.g., 22.522.522.5) is the diameter of the wheel rim in inches that the tire fits. 

Flotation and light truck (LT) sizes 

• Flotation size (e.g., 35 x 12.50 x 17):
  • Height: The first number is the tire's overall height in inches. 
  • Width: The second number is the width in inches. 
  • Rim Diameter: The third number is the wheel size in inches. 
• Light Truck (LT) size (e.g., LT285/70R17):
  • LT: Indicates it's a light truck tire. 
  • Width: The first number (285285285) is the width in millimeters. 
  • Aspect Ratio: The second number (707070) is the sidewall height as a percentage of the width. 
  • Construction Type: The 'R' stands for radial construction. 
  • Rim Diameter: The final number (171717) is the rim diameter in inches. 

Other important markings

• Load Index: A number that indicates the maximum weight a tire can support (e.g., 144144144 corresponds to a specific weight capacity). 
• Speed Rating: A letter that indicates the maximum speed the tire can safely handle (e.g., 'L' means 757575 mph). 
• DOT Code: A code that includes the manufacturer and a date of manufacture. 

Is a 275 tire the same as a 33?

No, a "275 tire" is not the same as a "33-inch tire" because the numbers represent different measurements in a tire's size. However, a specific metric size, such as a 275/60R20, can be nearly equivalent to a 33-inch diameter tire. The term "33" is a common, non-metric measurement for a tire's approximate overall diameter. 
Tire size explained

• Metric size (e.g., 275/60R20): This is a precise measurement with three parts: 
  • 275: The width of the tire in millimeters. 
  • 60: The aspect ratio, which is the height of the sidewall as a percentage of the width (60% of 275mm). 
  • R20: The radial construction and the diameter of the wheel in inches. 
• Non-metric size (e.g., 33x12.5R20): This is a common, more direct way to refer to a tire's approximate overall diameter: 
  • 33: The approximate total height of the tire in inches. 
  • 12.5: The width of the tire in inches. 
  • R20: The radial construction and the diameter of the wheel in inches. 

When they are similar

• A 275/60R20 tire is a close equivalent to a 33-inch tire, with a total diameter of approximately 33 inches. 
• Other metric sizes, like a 285/75R16, also result in a diameter close to 33 inches. 

Why it matters

• Compatibility: Always check the exact metric size of a tire to ensure it will fit your vehicle and is compatible with your suspension and wheel size.
• Speedometer accuracy: Changing your tire diameter significantly can cause your speedometer to be inaccurate. For example, larger tires will make you appear to be driving faster than you actually are. 

Can I look up tire size by VIN number?

No, a VIN number does not typically contain tire size information directly, but you can use a VIN lookup tool on many automotive websites to find the original equipment (OE) tire size for your vehicle's specific make, model, and trim. Other reliable methods include checking the sticker on your driver's side door jamb, your owner's manual, or the sidewall of your current tires. 
Ways to find your tire size

• Use a VIN lookup tool: Many websites, such as AutoZone, CARFAX, and Discount Tire, have VIN decoders that will provide your vehicle's specific trim and tire size. 
• Check the driver's side door jamb: This is the most common place to find a sticker with the original equipment tire size and recommended pressure. 
• Read your owner's manual: Your vehicle's manual will contain the recommended tire size for your specific model and trim. 
• Look at your current tires: The size is printed on the sidewall of your current tires, but be aware this may not be the original size if the tires have been changed. 
• Search online for your vehicle's make, model, and trim: This will help you find the correct specifications, as different trims of the same car can have different tire sizes.