From Tread to Ply: Understanding the Sidewall of Your Commercial Truck Tire

A Deep Dive into Tire Sidewall Information

When it comes to commercial truck tires, the sidewall is more than just rubber. It's a detailed map of critical information that can help you make informed decisions about tire maintenance, replacement, and performance. At Double Coin, we understand the importance of this information, and we're here to guide you through every aspect of reading a tire's sidewall.

The Anatomy of a Tire Sidewall

The sidewall of a tire contains a wealth of information encoded in various numbers, letters, and symbols. Here's a breakdown of what you'll find:

  1. Tire Size Designation
  2. Load Index and Speed Rating
  3. DOT Code
  4. Ply Rating
  5. Treadwear Indicators
  6. Additional Markings

1. Tire Size Designation

The tire size is perhaps the most crucial piece of information on the sidewall. It typically follows a format like 295/75R22.5. Here's what each part means:

  • 295: This is the tire's width in millimeters from sidewall to sidewall.
  • 75: This number represents the aspect ratio, which is the height of the tire's sidewall as a percentage of its width. In this case, the sidewall height is 75% of 295 mm.
  • R: This letter indicates the tire's construction type. 'R' stands for radial, which is the most common type for commercial truck tires.
  • 22.5: This is the diameter of the wheel rim in inches that the tire is designed to fit.

2. Load Index and Speed Rating

The load index and speed rating are usually found together at the end of the tire size, like 144/142L:

  • 144/142: These numbers indicate the tire's load-carrying capacity. For a single tire, the load index of 144 means it can carry up to 6,175 pounds, while 142 means it can carry up to 6,065 pounds when used in a dual configuration.
  • L: This letter represents the tire's maximum speed rating. 'L' corresponds to a maximum speed of 75 mph.

3. DOT Code

The Department of Transportation (DOT) code is a series of letters and numbers indicating the tire's compliance with all safety standards and its manufacturing details:

  • DOT: This prefix signifies that the tire meets DOT standards.
  • Plant Code: The next two letters identify the manufacturing plant.
  • Tire Size Code: This is a code for the tire size.
  • Optional Code: Up to four characters can be used by the manufacturer for internal tracking.
  • Date Code: The last four digits indicate the week and year the tire was manufactured. For example, 4821 means the tire was made in the 48th week of 2021.

4. Ply Rating

The ply rating, also known as the Load Range, indicates the tire's strength and capacity. Common load ranges for commercial truck tires are G, H, and L, with each range corresponding to a specific ply rating and load capacity.

5. Treadwear Indicators

Treadwear indicators are small, raised bars located in the grooves of the tire tread. When the tread wears down to the level of these bars, it's time to replace the tire. For commercial truck tires, maintaining proper tread depth is crucial for safety and performance.

6. Additional Markings

Other markings you might find include:

  • M+S: Indicates that the tire is suitable for Mud and Snow conditions.
  • Regroovable: This marking means the tire can be regrooved to extend its life.
  • Max Load and Pressure: These figures provide the maximum load the tire can handle and the maximum inflation pressure.

Why This Information Matters

Understanding the information on a tire's sidewall is essential for several reasons:

  • Safety: Ensuring the tire is properly matched to the vehicle's load and speed requirements helps prevent blowouts and accidents.
  • Performance: Choosing the right tire affects fuel efficiency, handling, and overall vehicle performance.
  • Maintenance: Knowing when to replace tires or regroove them can save money and extend tire life.


At Double Coin, we are committed to providing you with high-quality commercial truck tires designed for optimal performance and safety. By understanding how to read the sidewall of your tires, you can make better decisions about maintenance, replacement, and ensuring your fleet is always road-ready.

For more information on our range of commercial truck tires, visit our website. Safe travels!

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    About Double Coin

    Double Coin tires deliver exceptional value for a wide variety of commercial applications, including trucking, construction, mining, ports and agriculture. Our goal is to provide valuable information for those working in these industries.

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