Calculating Tire and Wheel Frequency
WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
For a vibration concern, use the vehicle speed to determine tire/wheel frequency and RPM. Calculate tire and wheel RPM and frequency by carrying out the following:
- Measure the diameter of the tire.
- Record the speed at which the vibration occurs.
- Obtain the corresponding tire and wheel RPM and frequency from the Tire Speed and Frequency Chart.
- If the vehicle speed is not listed, calculate the tire and wheel frequency as follows:
- 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 RPM listed for that tire diameter in the chart. Then divide that number by 60.
- For example, if calculating the frequency based on vehicle speed in km/h for a 64 km/h vibration with 835 mm tires, divide 64 km/h by 16 km/h = 4. Multiply 4 by 105 RPM = 420. Divide 420 by 60 seconds = 7 Hz at 64 km/h.
- If calculating the frequency based on vehicle speed in mph for a 40 mph vibration with 33 inch tires, divide 40 mph by 10 mph = 4. Multiply 4 by 105 RPM = 420. Divide 420 by 60 seconds = 7 Hz at 40 mph.
- The calculated frequency of 7 Hz is the first order tire and wheel vibration; the second order tire and wheel vibration would be twice this number at 14 Hz; the third order tire and wheel vibration would be 21 Hz; and so on.
TIRE SPEED AND FREQUENCY CHART
| Tire Diameter | Tire RPM/Hz | Tire RPM/Hz | Tire RPM/Hz | Tire RPM/Hz |
|---|---|---|---|---|
| mm (in) | @ 16 km/h (10 mph) | @ 80 km/h (50 mph) | @ 97 km/h (60 mph) | @ 113 km/h (70 mph) |
| 483 (19) | 182 | 910/15 | 1,092/18 | 1,274/21 |
| 508 (20) | 173 | 865/14 | 1,038/17 | 1,211/20 |
| 533 (21) | 165 | 825/14 | 990/16 | 1,155/19 |
| 560 (22) | 158 | 790/13 | 948/16 | 1,106/18 |
| 585 (23) | 151 | 755/13 | 906/15 | 1,057/18 |
| 610 (24) | 145 | 725/12 | 870/14 | 1,015/17 |
| 635 (25) | 139 | 695/12 | 834/14 | 973/16 |
| 660 (26) | 134 | 670/11 | 804/13 | 938/16 |
| 685 (27) | 129 | 645/11 | 774/13 | 903/15 |
| 710 (28) | 124 | 620/10 | 744/12 | 868/14 |
| 735 (29) | 119 | 595/10 | 714/12 | 833/14 |
| 760 (30) | 115 | 575/10 | 690/11 | 805/13 |
| 785 (31) | 111 | 555/9 | 666/11 | 777/13 |
| 810 (32) | 108 | 540/9 | 648/11 | 756/13 |
| 835 (33) | 105 | 525/9 | 630/10 | 735/12 |
| 864 (34) | 102 | 510/8 | 612/10 | 714/12 |