1. What is Pulse Per Mile?

Pulses Per Mile (PPM) is a measurement used in vehicle speed sensing systems to determine how many electronic pulses are generated per mile traveled. This value is crucial for proper calibration of speedometers and odometers.

2. How Does the Calculator Work?

The calculator uses the PPM equation:

Where:

• 63360 — Inches in one mile
• π — Mathematical constant Pi (~3.14159)
• Tire Diameter — Diameter of the tire in inches
• Axle Ratio — Vehicle's axle ratio
• Teeth — Number of teeth on the speed sensor tone ring

Explanation: The equation calculates how many times the speed sensor will pulse per mile based on tire revolutions and gear ratios.

3. Importance of PPM Calculation

Details: Accurate PPM calculation is essential for proper speedometer calibration, odometer accuracy, and correct operation of vehicle computer systems that rely on speed input.

4. Using the Calculator

Tips: Enter tire diameter in inches (measured or from manufacturer specs), the vehicle's axle ratio, and the number of teeth on the speed sensor tone ring. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure my tire diameter?
A: You can measure from ground to top of tire (unloaded) and multiply by 2, or use manufacturer specifications.

Q2: Where can I find my axle ratio?
A: Check your vehicle's manual, door jamb sticker, or axle identification tag. Some differential covers have this information stamped on them.

Q3: What if I change my tire size?
A: Changing tire size will affect your PPM and require speedometer recalibration to maintain accuracy.

Q4: How accurate is this calculation?
A: The calculation is mathematically precise, but actual results may vary slightly due to tire wear, pressure, and load.

Q5: Can this be used for any vehicle?
A: Yes, this calculation works for any wheeled vehicle with a speed sensor, including cars, trucks, and motorcycles.