1. What is the Tire Size Formula?

The tire size formula calculates the overall diameter of a tire based on the rim diameter and sidewall height. This measurement is crucial for ensuring proper fitment and performance of tires on vehicles.

2. How Does the Calculator Work?

The calculator uses the tire size formula:

Where:

• \( \text{Rim Diameter} \) — Diameter of the wheel rim (inches)
• \( \text{Sidewall Height} \) — Height of the tire sidewall (inches)

Explanation: The formula accounts for the fact that the tire adds height both above and below the rim, effectively doubling the sidewall height in the total diameter calculation.

3. Importance of Tire Size Calculation

Details: Correct tire sizing is essential for maintaining proper speedometer accuracy, vehicle clearance, handling characteristics, and overall safety.

4. Using the Calculator

Tips: Enter rim diameter and sidewall height in inches. Both values must be positive numbers. The calculator will compute the overall tire diameter.

5. Frequently Asked Questions (FAQ)

Q1: Why is overall tire diameter important?
A: It affects speedometer accuracy, gear ratios, and clearance between the tire and vehicle components.

Q2: How do I find my sidewall height?
A: Sidewall height is often listed in tire size markings (e.g., in P215/65R15, 65 is the aspect ratio which is percentage of the width).

Q3: What's a typical rim diameter range?
A: Passenger vehicles typically range from 14-22 inches, while trucks may go larger.

Q4: Does this work for all tire types?
A: The basic formula applies to all pneumatic tires, but specialty tires may have different considerations.

Q5: How precise should my measurements be?
A: For most applications, measurements to the nearest 0.1 inch are sufficient.