1. What is the Tire Size Calculator?

The Tire Actual Size Calculator determines the overall diameter of a tire based on its rim size, width, and aspect ratio. This measurement is crucial for proper vehicle fitment and performance.

2. How Does the Calculator Work?

The calculator uses the tire size formula:

Where:

• \( Rim \) — Rim diameter in inches
• \( Width \) — Tire width in millimeters
• \( Ratio \) — Aspect ratio (sidewall height as percentage of width)
• 25.4 — Conversion factor from mm to inches

Explanation: The formula calculates the sidewall height, converts it to inches, doubles it (for both sides of the rim), and adds the rim diameter.

3. Importance of Tire Size Calculation

Details: Correct tire diameter affects speedometer accuracy, gear ratios, clearance, and overall vehicle performance. Significant size differences can cause mechanical issues.

4. Using the Calculator

Tips: Enter rim size in inches, tire width in millimeters, and aspect ratio as a percentage. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Where can I find my tire size information?
A: Tire size is printed on the sidewall in the format: Width/Ratio R Rim (e.g., 225/50R17).

Q2: How accurate is this calculation?
A: It provides theoretical diameter. Actual diameter may vary slightly due to manufacturing tolerances and tread depth.

Q3: Why convert mm to inches?
A: Rim sizes are traditionally measured in inches while tire widths are in millimeters, requiring conversion for consistent units.

Q4: What's a typical aspect ratio?
A: Common ratios range from 30-75, with lower numbers indicating lower profile tires.

Q5: How much diameter difference is acceptable?
A: Generally within 3% of original size is recommended, but check your vehicle's specifications.