Calculating Tire and Wheel Frequency

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