1. What is a Tire Gear Ratio Calculator?

Definition: This calculator determines the gear ratio based on engine RPM, tire diameter, and vehicle speed.

Purpose: It helps automotive enthusiasts and mechanics calculate the optimal gear ratio for their vehicle setup.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( GR \) — Gear ratio (unitless)
• \( RPM \) — Engine revolutions per minute
• \( TD \) — Tire diameter (inches)
• \( S \) — Vehicle speed (mph)
• \( 1056 \) — Conversion constant

Explanation: The formula calculates how many times the driveshaft rotates for each rotation of the wheels.

3. Importance of Gear Ratio Calculation

Details: Proper gear ratio selection affects acceleration, fuel economy, towing capacity, and overall vehicle performance.

4. Using the Calculator

Tips: Enter the engine RPM at cruise, your tire diameter (measured or from specs), and desired cruising speed. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the 1056 constant in the formula?
A: It combines unit conversions (5280 feet/mile, 12 inches/foot, 60 minutes/hour) divided by π.

Q2: How do I measure my tire diameter?
A: Measure from ground to top of tire under load, or use: (Width × Aspect Ratio × 2 / 25.4) + Wheel Diameter.

Q3: What RPM should I use for calculation?
A: Use your engine's RPM at cruising speed for highway gear calculations, or peak torque RPM for performance setups.

Q4: What's a typical gear ratio range?
A: Passenger cars: 3-4:1, trucks: 3.5-4.5:1, performance vehicles: 3.7-4.1:1, rock crawlers: 5+:1.

Q5: Does this include transmission gear?
A: This calculates final drive ratio. Multiply by transmission gear ratio for complete analysis.