What size tires do I have on my truck?

Your truck’s tire size is printed on the sidewall of each tire and on the driver’s door jamb placard. Common sizes appear as a code like P265/70R17 or LT275/65R18; trucks can use different sizes per axle, so check all tires to confirm what you currently have.

Understanding your tire size is essential for choosing replacements that fit your vehicle, maintain proper clearance, and preserve performance. Below, you’ll find practical steps to locate the size, decode the markings, and assess compatibility before buying new tires.

Where to find your tire size

Use these sources to locate the size code on your truck. Each source may show the same or different sizes depending on axle configuration and how the vehicle was equipped from the factory.

• On the tire sidewall: look for a sequence like P265/70R17, LT275/65R18, or a variation such as 265/70R17 112T. The first number is the tire width in millimeters, the second is the aspect ratio, the "R" indicates radial construction, and the final number is the wheel diameter in inches.


• Door jamb placard (driver’s door frame): this label lists the recommended tire sizes for the vehicle as it came from the factory, sometimes specifying front/rear or axle-specific sizes.


• Owner’s manual or maintenance booklet: may reiterate the stock tire sizes and acceptable alternatives or upsize/downsizing guidance.


• Spare tire (if applicable): the spare may have a different size than the road tires; check it so you’re not surprised if you need to mount it.

If you find different sizes on different tires, start with the size listed on the door jamb placard or the factory recommendation for your exact axle configuration. When in doubt, match the size to the recommended spec for your vehicle.

Understanding tire size codes

Decoding the tire size code helps you compare options and verify compatibility with your truck’s wheels, clearance, and performance targets.

• Example breakdown: P265/70R17 112S. Here, P indicates a passenger-tire design (LT would indicate a light-truck tire). 265 is the width in millimeters. 70 is the aspect ratio (sidewall height as a percentage of width). R means Radial construction. 17 is the wheel diameter in inches. 112 is the load index, and S is the speed rating.


• Understanding the formats: P (passenger) vs LT (light-truck) vs T (temporary spare). The rest of the sequence (width/ratio/diameter) stays consistent across standard tires.


• Load index and speed rating: the two digits/letters after the size (e.g., 112S) indicate how much weight the tire can carry (load index) and the maximum safe speed (speed rating). Choose a load index equal to or higher than the OEM specification and a speed rating appropriate for your typical driving conditions.


• Other markings to note: some tires include letters like XL (extra load), or numbers that indicate designed performance (e.g., all-season, winter, mud-terrain). These affect traction, durability, and ride characteristics.

Decoding your tire size helps you pick a correct replacement. Always confirm that any new tire size matches the vehicle manufacturer’s recommendations for your specific trim and axle configuration.

What to consider if you want to change tire size

Upsizing or downsizing tires can affect handling, gearing, and accuracy of your speedometer, so proceed with care. Use these guidelines when evaluating a change in tire size.

• Clearance and handling: larger diameter or wider tires may rub on suspension components, fenders, or the body with full steering lock or suspension travel. Ensure there’s adequate clearance.


• Speedometer and gearing: changes in overall diameter can alter the indicated speed and engine RPM. You may need a recalibration or adjustment in the speedometer/odometer system.


• Wheel compatibility: verify bolt pattern, center bore, and offset (ET) to ensure the new wheels fit properly and don’t cause rubbing or brake caliper interference.


• Load rating and tire pressure: maintain a load index at least equal to the OEM spec and adhere to the recommended tire-pressure values for load and driving conditions.


• Trim and drivetrain considerations: four-wheel-drive, ABS sensors, and traction control systems can be sensitive to tire size changes; consult your vehicle’s manual or a tire professional before making a change.

If you’re unsure about selecting a different size, consult a tire shop or your vehicle manufacturer’s service department. They can confirm compatibility and help with reprogramming if needed.

How to confirm you’ve got the right tires for your truck

After identifying the size and any planned changes, verify the final setup with these checks. This helps ensure performance, safety, and compliance with manufacturer guidelines.

• Compare the size on all tires: if they differ, adhere to the most restrictive or OEM-recommended size per axle.


• Check clearance in wheel wells and with suspension components at full steering lock and compression.


• Verify proper wheel offset and hub compatibility with your truck’s brake components.


• Ensure TPMS (tire pressure monitoring system) sensors are compatible or recalibrated for the new size.

In practice, most drivers use the factory-recommended size or a recognized up-size within the OEM-approved range. Always test-drive after mounting new tires and have alignment checked to maintain safety and performance.

Summary

To determine your truck’s tire size, inspect the tire sidewalls and the door jamb placard for the official code (for example, P265/70R17 or LT275/65R18), then decode the numbers to understand width, aspect ratio, construction, and wheel diameter. If you’re changing sizes, consider clearance, gearing, and drivetrain implications, and verify wheel compatibility and load ratings. When in doubt, consult a tire professional to ensure a safe, compliant fit.

What is the 7 7 rule for tires?

If you leave them on too late, your winter tires will degrade quickly. So, when is the right time to swap? The rule of thumb is 7-for-7: wait until there are seven consistent days at 7 degrees Celsius. The reverse is also true for transitioning to winter.

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. 

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. 

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.