1. What is a Speed Increase Ratio Calculator for Tires?

Definition: This calculator determines the speed ratio when changing tire sizes by comparing the new tire diameter to the old tire diameter.

Purpose: It helps vehicle owners and mechanics understand how changing tire sizes affects speedometer readings and vehicle performance.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Speed Ratio — Dimensionless ratio indicating speed change
• New Tire Diameter — Diameter of the new tires (meters)
• Old Tire Diameter — Diameter of the original tires (meters)

Explanation: A ratio greater than 1 means your vehicle will travel faster than the speedometer indicates. A ratio less than 1 means your vehicle will travel slower than the speedometer indicates.

3. Importance of Tire Speed Ratio Calculation

Details: Proper calculation ensures accurate speedometer readings, maintains proper gearing, and helps avoid transmission strain or incorrect odometer readings.

4. Using the Calculator

Tips: Measure or look up the diameters of both your old and new tires in meters. Enter both values to calculate the speed ratio.

5. Frequently Asked Questions (FAQ)

Q1: How does tire diameter affect speed?
A: Larger tires cover more distance per rotation, effectively increasing speed at the same RPM compared to smaller tires.

Q2: Where can I find my tire diameter?
A: Tire diameter can be calculated from tire size markings or measured directly. Many online tire size calculators can convert tire codes to diameter.

Q3: What's considered a significant speed ratio change?
A: A ratio below 0.97 or above 1.03 may require speedometer recalibration to maintain accuracy.

Q4: Does this affect fuel economy?
A: Yes, larger tires typically decrease fuel economy due to increased rotational mass and changed final drive ratio.

Q5: How does this relate to gear ratios?
A: The speed ratio effectively changes your final drive ratio. Larger tires act like higher gearing, while smaller tires act like lower gearing.