Servicing Multi-Piece & Single-Piece Rims

A large truck or equipment tire holds enormous energy. When a rim part separates or a tire explodes during inflation, pieces fly out with enough force to kill. OSHA has a specific standard for servicing these rim wheels, and every tire technician needs to know it.

• Tire technicians
• Mechanics
• Fleet shops

Who the rule covers

OSHA’s rim wheel standard covers servicing (mounting, demounting, inflating, inspecting) of multi-piece and single-piece rim wheels on large vehicles like trucks, tractors, trailers, buses and off-road machines. It doesn’t cover car or light-truck tires.

The trajectory

The trajectory is the area a rim part or the blast is likely to go if it separates. For multi-piece rims, that’s mostly straight out from the side of the tire. Stay out of it while inflating or working on a pressurized tire.

Key rules

• Training: only trained workers may service rim wheels, using the OSHA/NHTSA charts or maker’s manual, which must be available in the work area.
• Deflate completely by removing the valve core before demounting. Deflate before removing a wheel from the axle if the tire was run at 80% or less of its recommended pressure, or if damage is obvious or suspected.
• Restraining device: inflate tires on multi-piece rims (and single-piece rims off the vehicle, as required) only inside a cage or restraining device, or with the tire secured to the vehicle as the standard allows.
• Clip-on chuck with an in-line valve and gauge, and enough hose to stand outside the trajectory.
• Check the components: match rim parts by size and type; no cracked, bent, corroded or mismatched parts.
• Seat properly: don’t try to correct a ring or bead seating by hammering while the tire is pressurized. Deflate first.
• Never heat, weld or cut on a rim with a tire mounted.

Before inflating

• Rim components match and are undamaged; lock ring fully seated
• Tire in a restraining cage (or secured as the standard allows)
• Clip-on chuck, in-line valve and gauge on a long enough hose
• You and everyone else out of the trajectory
• Inflating to the maker’s seating pressure, then checking before final inflation

On the road

Drivers and techs should report sidewall bulges, cuts and tires run flat or very low. A tire damaged by running underinflated can fail explosively later. See Tire Blowouts.

Last updated: October 2, 2026