1. What is the Final Drive Calculator?

The Final Drive Calculator with Tire Size helps determine how changing your tire diameter affects your vehicle's final drive ratio. This is important for maintaining proper gearing when upgrading or changing tire sizes.

2. How Does the Calculator Work?

The calculator uses the following equation:

Where:

• \( Ratio \) — Original gear ratio (dimensionless)
• \( New Tire Diameter \) — Diameter of new tires (inches)
• \( Old Tire Diameter \) — Diameter of original tires (inches)

Explanation: The equation accounts for how changing tire diameter affects the effective gear ratio, which impacts acceleration, top speed, and engine RPM at given speeds.

3. Importance of Effective Ratio Calculation

Details: Calculating the effective ratio helps maintain proper vehicle performance when changing tire sizes. Larger tires effectively raise the gear ratio (numerically lower), while smaller tires effectively lower the gear ratio (numerically higher).

4. Using the Calculator

Tips: Enter your original gear ratio, new tire diameter, and old tire diameter. All values must be positive numbers. Tire diameters should be measured in inches.

5. Frequently Asked Questions (FAQ)

Q1: Why does tire size affect gear ratio?
A: Larger tires cover more ground per rotation, effectively making your gearing taller (like having a higher numerical gear ratio).

Q2: How do I measure tire diameter?
A: You can calculate it using the tire size numbers (e.g., 275/60R15) or measure the actual mounted tire height.

Q3: What's a typical effective ratio change?
A: A 10% increase in tire diameter will make your effective ratio about 10% taller (numerically lower).

Q4: How does this affect my speedometer?
A: Larger tires will make your speedometer read slower than actual speed, while smaller tires make it read faster.

Q5: Should I change my gears after changing tire size?
A: Many enthusiasts recommend matching the effective ratio to your original setup for optimal performance.