1. What is a Bigger Tire Size Calculator?

Definition: This calculator determines how your vehicle's speed reading changes when you install larger tires than the original equipment.

Purpose: It helps vehicle owners understand how tire size changes affect speedometer accuracy and actual vehicle speed.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S_{new} \) — Actual speed with new tires (mph)
• \( S_{old} \) — Speedometer reading (mph)
• \( TD_{new} \) — New tire diameter (inches)
• \( TD_{old} \) — Original tire diameter (inches)

Explanation: Larger tires cover more distance per rotation, causing your vehicle to travel faster than the speedometer indicates.

3. Importance of Tire Size Calculation

Details: Proper tire size calculations ensure accurate speed readings, correct odometer readings, and proper transmission shifting.

4. Using the Calculator

Tips: Enter your speedometer reading, original tire diameter, and new tire diameter. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why does speed change with bigger tires?
A: Larger tires rotate fewer times per mile, causing your vehicle to travel faster than the speedometer indicates.

Q2: How do I find my tire diameter?
A: Check tire specifications or use this formula: (Width × Aspect Ratio × 2 ÷ 25.4) + Wheel Diameter.

Q3: Will this affect my odometer?
A: Yes, your odometer will under-report actual mileage with larger tires.

Q4: How much difference is significant?
A: A 3% or greater difference typically requires speedometer recalibration.

Q5: Does this affect fuel economy calculations?
A: Yes, your MPG calculations will be inaccurate unless you account for the tire size change.