Frequency Calculations
Calculating Tire and Wheel Frequency
For a vibration concern, use the vehicle speed to determine tire/wheel frequency and Revolutions Per Minute (RPM). Calculate the tire and wheel Revolutions Per Minute (RPM) and frequency by carrying out and following:
- Measure the diameter of the tire.
- Record the speed at which the vibration occurs.
- Obtain the corresponding tire and wheel Revolutions Per Minute (RPM) and frequency from the Tire Speed and Frequency Chart.
- If the vehicle speed is not listed, divide the vehicle speed at which the vibration occurs by 16 km/h (10 mph). Multiply that number by the 16 km/h (10 mph) tire Revolutions Per Minute (RPM) listed for that tire diameter in the chart. Then divide that number by 60. For example: a 40 MPH (Miles Per Hour) vibration with 835 mm (33 in) tires. 40 divided by 10 = 4. Multiply 4 by 105 = 420 Revolutions Per Minute (RPM). Divide 420 Revolutions Per Minute (RPM) by 60 seconds = 7 Hertz (Hz) at 40 MPH (Miles Per Hour).
Tire Speed and Frequency Chart
| Tire Diameter | Tire Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below | Tire Revolutions Per Minute (Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below | Tire Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below | Tire Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below |
|---|---|---|---|---|
| in (mm) | 9.9 mph (16 km/h) | 49.7 mph (80 km/h) | 60.3 mph (97 km/h) | 70.2 mph (113 km/h) |
| 19.02 in (483 mm) | 182 | 910/15 | 1092/18 | 1274/21 |
| 20.00 in (508 mm) | 173 | 865/14 | 1038/17 | 1211/20 |
| 20.98 in (533 mm) | 165 | 825/14 | 990/16 | 1155/19 |
| 22.05 in (560 mm) | 158 | 790/13 | 948/16 | 1106/18 |
| 23.03 in (585 mm) | 151 | 755/13 | 906/15 | 1057/18 |
| 24.02 in (610 mm) | 145 | 725/12 | 870/14 | 1015/17 |
| 25.00 in (635 mm) | 139 | 695/12 | 834/14 | 973/16 |
| 25.98 in (660 mm) | 134 | 670/11 | 804/13 | 938/16 |
| 26.97 in (685 mm) | 129 | 645/11 | 774/13 | 903/15 |
| 27.95 in (710 mm) | 124 | 620/10 | 744/12 | 868/14 |
| 28.94 in (735 mm) | 119 | 595/10 | 714/12 | 833/14 |
| 29.92 in (760 mm) | 115 | 575/10 | 690/11 | 805/13 |
| 30.91 in (785 mm) | 111 | 555/9 | 666/11 | 777/13 |
| 31.89 in (810 mm) | 108 | 540/9 | 648/11 | 756/13 |
| 32.87 in (835 mm) | 105 | 525/9 | 630/10 | 735/12 |
| 34.02 in (864 mm) | 102 | 510/8 | 612/10 | 714/12 |