Tyre Size Calculator (Width/Aspect Ratio/Rim) |

Tyre Size Calculator (Width/Aspect Ratio/Rim)

Tyre Size Formula:

\[ \text{Overall Diameter} = \left( \frac{\text{Width} \times \text{Aspect Ratio}}{100} \times 2 \right) + \text{Rim Diameter} \]

Sidewall Height:

Overall Diameter:

Circumference:

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1. What is a Tyre Size Calculator?

Definition: This calculator determines key tyre dimensions based on the width, aspect ratio, and rim diameter.

Purpose: It helps vehicle owners, mechanics, and enthusiasts understand tyre specifications and compare different tyre sizes.

2. How Does the Calculator Work?

The calculator uses these formulas:

\[ \text{Sidewall Height} = \frac{\text{Width} \times \text{Aspect Ratio}}{100} \] \[ \text{Overall Diameter} = \left( \frac{\text{Sidewall Height} \times 2}{25.4} \right) + \text{Rim Diameter} \] \[ \text{Circumference} = \text{Overall Diameter} \times \pi \]

Where:

Width — Tyre width in millimeters (e.g., 205 in 205/55R16)
Aspect Ratio — Sidewall height as percentage of width (e.g., 55 in 205/55R16)
Rim Diameter — Wheel diameter in inches (e.g., 16 in 205/55R16)

3. Importance of Tyre Size Calculation

Details: Proper tyre sizing affects vehicle handling, speedometer accuracy, clearance, and overall safety.

4. Using the Calculator

Tips: Enter the three main tyre size components (width in mm, aspect ratio %, rim diameter in inches) as found on your tyre sidewall.

5. Frequently Asked Questions (FAQ)

Q1: Where do I find these numbers on my tyre?
A: Look on the tyre sidewall for a format like "205/55R16" - 205 is width, 55 is aspect ratio, 16 is rim diameter.

Q2: Why convert to inches for diameter?
A: Rim diameters are traditionally measured in inches in the tyre industry standard.

Q3: How does tyre size affect my vehicle?
A: Changing sizes can impact speedometer accuracy, fuel economy, handling, and may cause clearance issues.

Q4: What's the 25.4 in the formula?
A: This converts millimeters to inches (1 inch = 25.4 mm) since rim diameter is in inches.

Q5: Can I use this for plus-sizing wheels?
A: Yes, it helps maintain overall diameter when changing wheel sizes while adjusting tyre profile.