1. What is a Tyre Size Calculator?

Definition: This calculator determines the overall diameter of a tyre based on its width, aspect ratio, and rim diameter.

Purpose: It helps vehicle owners compare tyre sizes when considering replacements or upgrades.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Width — Tyre section width in millimeters
• Aspect Ratio — Sidewall height as percentage of width
• Rim Diameter — Wheel diameter in inches

Explanation: The calculation converts the metric measurements to determine the total diameter in inches.

3. Importance of Tyre Size Calculation

Details: Correct tyre sizing ensures proper vehicle handling, speedometer accuracy, and prevents clearance issues.

4. Using the Calculator

Tips: Enter the tyre width in mm, aspect ratio (default 65%), and rim diameter (default 16 inches). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does the aspect ratio mean?
A: The aspect ratio is the sidewall height expressed as a percentage of the tyre's width (e.g., 65 means the sidewall is 65% of the width).

Q2: How do I find my current tyre size?
A: Look on your tyre sidewall for numbers like "205/55R16" where 205 is width, 55 is aspect ratio, and 16 is rim diameter.

Q3: What's the maximum size difference allowed?
A: Generally, the new tyre diameter should be within ±3% of the original diameter for safe operation.

Q4: Why are some measurements in mm and others in inches?
A: This is the standard format used in the tyre industry worldwide.

Q5: Does this calculator account for wheel width?
A: No, this calculates theoretical diameter. Actual mounted dimensions may vary slightly based on wheel width.