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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 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.

Wheel and Tire Terminology

 

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

Toyota Truck Steel Wheel with red mark in the "Safety Hump"Mod Steel Wheel with red mark in the "Safety Hump"

 

 

3.  Aspect Ratio:

Wheel and Tire Terminology

 

 

4. Wheel Offset: 

Wheel and Tire Terminology

 

 

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

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