1. What is a Tire Size Conversion Calculator?

Definition: This calculator determines the equivalent tire size when changing aspect ratios or wheel diameters.

Purpose: It helps automotive professionals and enthusiasts maintain proper speedometer calibration and vehicle performance when changing tire sizes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Equivalent Size — New tire diameter (inches)
• Original Diameter — Current tire diameter (inches)
• Ratio Adjustment — Size conversion factor

Explanation: The original tire diameter is multiplied by the ratio adjustment to calculate the equivalent size that maintains similar overall performance characteristics.

3. Importance of Tire Size Conversion

Details: Proper tire size conversion ensures accurate speedometer readings, maintains proper gearing, and prevents clearance issues.

4. Using the Calculator

Tips: Enter the original tire diameter in inches and the ratio adjustment factor (default 1.0). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I find my original tire diameter?
A: Check your tire sidewall for size markings (e.g., 225/45R17) and use a tire size calculator to determine diameter.

Q2: What's a typical ratio adjustment?
A: Start with 1.0 for direct comparison. Common adjustments range from 0.95 to 1.05 for minor size changes.

Q3: When would I need to convert tire sizes?
A: When changing wheel diameters, aspect ratios, or when upsizing/downsizing tires while maintaining overall diameter.

Q4: How does this affect my speedometer?
A: A larger equivalent size will cause speedometer to read slower than actual speed, and vice versa.

Q5: What's the maximum recommended size change?
A: Generally within ±3% of original diameter to avoid significant speedometer errors and mechanical issues.