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Tire, Axle Ratio & Sensor Pulses per Mile

Estimate pulses per mile from wheel revolutions, axle reduction and sensor teeth under a stated sensor-position model.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Formula and method

At 800 wheel revolutions per mile, a 4:1 axle ratio and 40 pulses per sensor-shaft revolution give 128,000 pulses per mile.

Pulses per mile = wheel revolutions per mile × axle ratio × teeth; wheel revolutions per mile = 63,360 ÷ (π × tire diameter in inches)

Worked example

Enter these known values and leave the other values blank.

Wheel revolutions per mile
800
Sensor-shaft revolutions per wheel revolution
4
Sensor teeth / pulses per shaft revolution
40
Effective tire diameter
25.21 in
Pulses per mile
128000

Assumptions and limitations

  • The sensor is assumed to produce one pulse per tooth and rotate at the entered ratio relative to the wheel. The familiar axle-ratio form applies when the sensor measures the shaft upstream of that reduction.
  • For a sensor rotating with the wheel, use the appropriate ratio of 1 instead of multiplying by an unrelated axle reduction. Additional signal processing can change the effective pulse count.
  • All quantities must be positive and the tooth count must be a whole number. The tire formula assumes a circular rolling circumference without slip or deformation.
  • Use measured wheel revolutions per mile when available. This arithmetic does not identify a vehicle’s sensor location or certify a speedometer calibration.

Common questions

How can I avoid relying on nominal tire diameter?

Enter measured wheel revolutions per mile instead. The pulse total then follows directly from that count, the sensor-to-wheel ratio and pulses per sensor revolution.

Can I solve for the sensor ratio?

Yes. Enter the pulse total, wheel revolutions per mile and whole-number tooth count. A total of 128,000 with 800 revolutions and 40 teeth gives a ratio of 4.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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