Method and system for determining non-uniformity characteristics of a vehicle tire and rim

A method of determining force variation attributable to a tire in a wheel assembly wherein the tire is coupled to a rim, the method implemented on a tire changer including a controller, method comprising:

• determining a first force variation of the wheel assembly while the tire is in a first rotational position with respect to the rim;
• rotating the tire with respect to the rim to a second rotational position with respect to the rim;
• determining a second force variation of the wheel assembly while the tire is in the second rotational position;
• and
• determining, with the controller, a force variation component associated with the tire using the determined first force variation and the determined second force variation.

A wheel assembly service system comprising:

• a rotatable spindle configured to receive a wheel assembly, the wheel assembly comprising at least a rim and a tire;
• and
• a controller configured to:
• determine a first non-uniformity of the wheel assembly;
• initiate rotation of the tire with respect to the rim;
• determine a second non-uniformity of the wheel assembly with the tire rotated with respect to the rim;
• and
• determine a non-uniformity component associated with the rim utilizing said first determined non-uniformity and said second determined non-uniformity.

A method for measuring the non-uniformity of a wheel assembly that includes a tire coupled to a rim, said method implemented with a wheel assembly service system including a controller, and said method comprising:

• determining a first non-uniformity of the wheel assembly;
• rotating the tire with respect to the rim;
• determining a second non-uniformity of the wheel assembly with the tire rotated with respect to the rim;
• and
• determining, with the controller, a non-uniformity component associated with the rim utilizing the determined first non-uniformity and the determined second non-uniformity.

A wheel assembly service system comprising:

• a rotatable spindle configured to receive a wheel assembly, the wheel assembly including at least a rim and a tire;
• and
• a controller configured to determine a force variation component associated with at least one of the rim and the tire without measuring a rim runout;
• wherein the wheel assembly service system is configured as a tire changer machine.