1. What is the Wheel Speed Equation?

The Wheel Speed equation calculates vehicle speed based on engine RPM and tire circumference, accounting for changes from lift kits or larger tires. It helps determine how speedometer readings will be affected by modifications.

2. How Does the Calculator Work?

The calculator uses the Wheel Speed equation:

Where:

• \( rpm \) — Engine revolutions per minute
• \( new\_circ \) — New tire circumference in inches
• 336 — Conversion factor combining multiple unit conversions

Explanation: The equation converts rotational speed at the wheels to linear vehicle speed, accounting for the distance traveled per revolution (circumference).

3. Importance of Wheel Speed Calculation

Details: Accurate speed calculation is crucial after installing lift kits or larger tires to ensure proper speedometer calibration, transmission shifting, and overall vehicle performance.

4. Using the Calculator

Tips: Enter engine RPM and new tire circumference in inches. All values must be valid (RPM > 0, circumference > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why is the 336 factor used?
A: It combines unit conversions (minutes to hours, inches to miles) and gear ratio constants into a single factor.

Q2: How do I measure tire circumference?
A: Measure from ground to axle center (radius), multiply by 2π, or roll the tire one revolution and measure distance traveled.

Q3: How much will my speedometer be off after larger tires?
A: Speedometer error = (new circumference / original circumference - 1) × 100%. A calculator helps determine exact correction needed.

Q4: Does this account for gear ratio changes?
A: This basic calculation assumes stock gearing. For modified gear ratios, additional calculations are needed.

Q5: What's typical circumference for common tire sizes?
A: Example: 31" tire ≈ 97-98", 33" ≈ 103-104", 35" ≈ 109-110" circumference (varies by brand/model).