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Wheel and Tire Terms & Diagrams to help you understand

what they are talking about:

1. Diagram with technical terms describing parts of wheels:

               Note "Safety Humps" in diagram and picture below

The Safety Hump (AKA Bead Bump) is required by DOT to help hold the bead of the tire against the flange in case of blowout air pressure loss, while the vehicle is decelerating, to decrease the possibility of tire shredding and complete loss of control.

Hubcap mounting clips seat into the groove formed by the Safety Hump, marked in red in the picture below, for increased hold on the wheel.  If the Safety Hump groove is not present, as in some cheap wheels imported from India, Brazil, and other sources, hubcaps or trim rings may not hold the wheel as well as would normally be expected.

 

2.  "Safety Hump" Marked in Red in the pictures below

 

 

3.  Another Wheel Diagram:

 

 

4.  Aspect Ratio:

 

 

5. Wheel Offset: 

 

 

   Standard Steel Wheel    Eight-Spoke Steel Wheel         Mini-Mod Steel Wheel

                     

 

 

This picture shows a Cut-away Hubcap mounted on a wheel, intended to show how hubcaps are designed to bridge over the space occupied by wheel weights, so that most wheel weights are no problem with most hubcaps.

However, as of 2013, all states will require conversion to Non-Lead Wheel weights, which are made of lighter metals like iron or zinc,

and some of these may be thicker than those shown.