There are several critical measurements to take into account when selecting a wheel or when replacing your stock wheels with aftermarket wheels (wheels and rims being used interchangeably in this article). Among these important measurements are:
This is the total wheel diameter when measured from bead seat to bead seat. When replacing tires you of course must know the wheel diameter, but this will be stamped on the old tires. If you are browsing through a stack of wheels that are not stamped an easy way to determine the diameter is to measure the maximum diameter from rim to rim and then with a ruler measure the distance from the rim down to the bead seat. Subtract twice the distance which you measured down to the bead seat from the rim to rim diameter and you will have the correct wheel diameter. Wheel diameter is a critical consideration when changing or altering brake components. It is also believed by many that 15" and 16" wheels have a superior bead design and better bead retention than 16.5" or 17" wheels due to a raised inner ridge or "safety bead" that helps to keep the tire bead in place.
Read more of Basic Wheel Facts in the 4x4Wire Archives.