Magnetism of automotive wheels with pneumatic radial tires

This paper shows enhancement of knowledge about magnetic flux density of automotive wheels with radial pneumatic tires equipped with ferromagnetic belt made of tangled steel wires. The investigations were focused on the measurement of magnetic flux density vector (B) over tire's tread using sensor ability to measure 3 Cartesian projections of B. The other aim of the article is to introduce the prototype of a measuring device as well as measurement technique the purpose of which is to obtain a single or a collection of so called magnetic profiles. Circumferential and crosswise to the tread magnetic profiles and scans over tread surface were presented and analyzed. Moreover, magnetic profile's parameters were proposed in order to quantitatively characterize magnetic flux density changes in circumferential profiles. Usefulness of them was analyzed and discussed in the context of the measurement technique and the practical utilization. The results revealed that the magnetic flux density is not uniform over tire's tread surface and the “magnetic surface” is not anisotropic but highly directional. What is more, there are preferred sensor's locations and measurement directions. The Authors also pointed out some potential application of gained knowledge in domain of vehicle state measurement such as speed, distance and wheel slip.