Low frequency magnetic fields induced by car tire magnetization.

Alternating magnetic fields have been measured in a variety of different cars, the dominant contribution being from magnetized tires. Magnetic field strengths have been measured as a function of frequency directly at the tires and at different positions in rolling cars. Measurements at the tires showed field strengths up to 100 microtesla (microT). In the interior of rolling cars, close to the wheels at foot regions and at the back seat, field strengths of several microT were obtained in the 10-200 hertz (Hz) frequency domain. In some cases measured field values were considerably higher than those found in previous studies. Purposely magnetizing single tires made it possible to study the influence of various parameters. Degaussed tires retained low field values over prolonged time under conditions of normal use.