Stem Casters

Remove the existing caster and examine the stem. If it has threads, it is a threaded stem -- note the thread diameter and pitch. If it has a smooth shaft with a small metal or plastic ring near the base, it is a grip ring stem -- measure the stem diameter. If it has a square or ribbed shoulder at the top, it is a grip neck stem. If it has a rubber bushing that expands inside tubing, it is an expanding adapter. When in doubt, measure the stem diameter and socket inside diameter.

The 7/16" grip ring stem is the most widely used size. It is the standard for most wire shelving, institutional carts, and light-duty rack systems. Some older or specialty equipment uses 3/8" or 1/2" grip ring stems. Always measure before ordering.

Not directly, but you can use caster sockets or brackets. A caster socket is a receptacle that you weld or bolt to the equipment, creating a socket for a grip ring or threaded stem caster. This is a common solution when adding casters to steel tubing or fabricated equipment that was not originally designed for top-plate mounting.

Stem casters typically range from 75 lbs to 500 lbs per caster, depending on the stem type and wheel size. Threaded stems in larger diameters (1/2" and above) support the highest loads in this category. Grip ring stems are generally limited to lighter loads because the friction-fit connection has less structural strength than a bolted or threaded connection.