Tire Size Conversion Calculator

Tire Size Conversion Calculator

Welcome to the Tire Size Conversion Calculator! Whether you’re an automotive enthusiast, a mechanic, or simply someone looking to understand tire sizes better, our tool is here to help you convert between metric and standard tire sizes quickly and accurately.

Why Use a Tire Size Conversion Calculator?

Tire sizes can be confusing, especially when comparing metric sizes like 225/45R17 with standard sizes like 28×9.50-15. This calculator simplifies the process, allowing you to input your tire specifications in one format and instantly see the equivalent size in the other format. This can be incredibly useful when shopping for new tires, ensuring compatibility and helping you make informed decisions.

How to Use the Calculator

  1. Select the Tire Size Format:
    • Use the dropdown menu to choose between Metric (e.g., 225/45R17) and Standard (e.g., 28×9.50-15) formats.
  2. Input Your Tire Specifications:
    • For Metric format:
      • Tire Width (mm): The width of the tire in millimeters.
      • Aspect Ratio (%): The height of the tire’s sidewall as a percentage of the width.
      • Wheel Diameter (inches): The diameter of the wheel in inches.
    • For Standard format:
      • Overall Diameter (inches): The total diameter of the tire in inches.
      • Tire Width (inches): The width of the tire in inches.
      • Aspect Ratio: The ratio of the tire’s height to its width.
  3. Click Convert:
    • After entering your tire specifications, click the Convert button to see the equivalent tire size in the other format.


  • Metric to Standard Conversion:
    • Input: 225/45R17
    • Output: Standard: 25.97×8.86-0.45
  • Standard to Metric Conversion:
    • Input: 28×9.50-15
    • Output: Metric: 241/95R15

Understanding Tire Sizes

Metric Format (225/45R17)

  • 225: Tire width in millimeters.
  • 45: Aspect ratio (sidewall height is 45% of the tire width).
  • R17: Radial construction with a 17-inch wheel diameter.

Standard Format (28×9.50-15)

  • 28: Overall diameter of the tire in inches.
  • 9.50: Tire width in inches.
  • 15: Wheel diameter in inches.

Why Tire Size Matters

Choosing the right tire size is crucial for several reasons:

  • Safety: Proper tire size ensures optimal handling, braking, and traction.
  • Performance: The right size affects the vehicle’s performance, including speedometer accuracy and fuel efficiency.
  • Compatibility: Ensures that tires fit correctly on the wheels and within the wheel wells without rubbing.

Tire Size Conversion Formula

Understanding how the conversion works can be helpful:

  • Metric to Standard:
    • Overall Diameter (in inches) = (Tire Width (mm) * Aspect Ratio / 100 * 2 / 25.4) + Wheel Diameter (inches)
    • Tire Width (in inches) = Tire Width (mm) / 25.4
  • Standard to Metric:
    • Tire Width (mm) = Tire Width (inches) * 25.4
    • Aspect Ratio (%) = Aspect Ratio * 100

Common Tire Sizes

Here are some common tire sizes and their conversions to help you get started:

  • Metric: 205/55R16, 225/45R17, 245/40R18
  • Standard: 27×8.50-14, 30×9.50-15, 31×10.50-15

Benefits of Using the Calculator

  • Accuracy: Ensures you get the correct tire size conversion for safety and performance.
  • Convenience: Saves time and effort in manual calculations.
  • User-Friendly: Easy-to-use interface with clear input fields and instructions.

Additional Resources

  • Tire Size Chart: Check out our comprehensive tire size chart for more information on tire dimensions.
  • Tire Buying Guide: Read our guide on how to choose the right tires for your vehicle.
  • Tire Maintenance Tips: Learn how to maintain your tires to ensure longevity and performance.
  • Contact Us: Have questions? Contact our support team for assistance.

Frequently Asked Questions (FAQs)

Q: Can I use this calculator for off-road tires? A: Yes, the calculator can be used for both on-road and off-road tires. Ensure you input the correct specifications for accurate results.

Q: What if my tire size is not listed? A: You can manually input your tire size into the calculator. If you need further assistance, please contact our support team.

Q: How often should I check my tire size and condition? A: Regularly inspect your tires every month and before long trips. Check for wear and tear, proper inflation, and alignment.

Q: Why does the aspect ratio matter? A: The aspect ratio affects the tire’s sidewall height, which influences ride comfort, handling, and overall performance.


Thank you for using the Tire Size Conversion Calculator! We hope it makes your tire shopping experience easier and more enjoyable. Whether you’re converting tire sizes for your car, truck, SUV, or off-road vehicle, our calculator provides quick and accurate results to help you make informed decisions. Happy driving!

About the Author

Dan Collins
Dan Collins

Rooted in a familial history of garage work, Dan Collins pursued his passion and earned a Master’s in Mechanical Engineering in 2003. His journey in the automotive world was fueled by a fascination with cutting-edge companies offering products beyond the ordinary. At Cars Bibles, Dan utilizes his professional standpoint to... Read full bio

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