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Tire Markings: Decoding Your Tire's Secrets with Flathouse Tires

Hello, New Jersey! FHTMotorsports here, and I'm excited to welcome you to the Flathouse Tires blog, where we combine expertise and passion for everything on wheels. Our new location is coming soon, and we're eager to become your go-to spot for all your tire needs. 

Today, we're delving into the world of tire markings—an essential guide to help you understand what your tires are telling you.

Tire Markings Simplified 

Tire Type

Start by identifying the tire type, marked by a letter on the sidewall. "P" denotes passenger vehicles, including cars and SUVs, while "LT" stands for Light Truck tires. Choosing the correct tire type for your vehicle is crucial for optimal performance and safety.

Tire Width

Following the tire type, you'll see a three-digit number indicating the tire's width in millimeters, measured from sidewall to sidewall. For example, 215 means the tire is 215 millimeters wide. Wider tires are commonly used on performance cars for better grip and handling at higher speeds.

 Aspect Ratio

The aspect ratio represents the height of the tire's cross-section as a percentage of its width. A marking of 65 means the height is 65% of the tire's width. Lower aspect ratios (70 or below) are favored for performance driving, offering quicker handling and more precise control.


The construction type is indicated by a letter. "R" stands for radial construction, where body ply cords run radially across the tire. "B" denotes bias construction, with body ply cords running diagonally. Radial tires are preferred for their durability and performance.

Rim Diameter

This number, given in inches, specifies the size of the wheel the tire fits. A 15-inch rim diameter means the tire is designed for a 15-inch wheel. Ensuring the correct rim diameter is essential for safety and performance.

Now to the Performance Indicators

Speed Ratings

Speed ratings are alphabetical designations that indicate the maximum speed a tire can handle. This rating ensures your tires can match your vehicle's speed capabilities safely. For example, a tire marked "95S" is certified for higher speeds. Always replace tires with ones that have an equivalent or higher speed rating.

Load Index

The load index is a numerical value indicating the maximum weight a tire can support when properly inflated. This is especially important for trucks and SUVs. Refer to your vehicle’s placard or owner's manual to match the correct load index.

A bit of the Boring stuff…. Government Regulations: UTQG

The Uniform Tire Quality Grading System (UTQG) ensures you’re informed about three key performance factors:


This grade compares the expected lifespan of the tire's tread. A tire with a treadwear grade of 200 should last twice as long as one graded 100 under test conditions. Actual mileage will vary based on usage conditions.


Traction grades (A, B, C) indicate a tire's ability to stop on wet pavement. These grades are based on straight-line braking tests, with A being the best.

Temperature Resistance

The temperature grade measures the tire's ability to dissipate heat. Tires are rated A (best), B, or C (acceptable). Proper heat dissipation is crucial for preventing tire failure, especially in high-speed or hot conditions.

The Bottom Line

Before replacing your tires, always consult your vehicle’s manual and adhere to the manufacturer’s recommendations. Incorrect tire sizes or types can significantly affect your vehicle’s handling and safety. At Flathouse Tires, we’re here to help you make the right choice. Our experts can guide you in selecting tires that ensure proper clearance, load carrying capacity, and inflation pressure. Never exceed the maximum load capacity and inflation pressure listed on the tire’s sidewall. Drive safely, obey traffic laws, and avoid sudden, sharp turns or lane changes to maintain control of your vehicle.

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Got questions? Don’t hesitate to reach out. Our tire experts are ready to answer any tire-related inquiries you may have.

Drive smart, drive safe, and let Flathouse Tires keep you rolling.

Rodrigo Gazali

Flathouse Tires New Jersey

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