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Alert: Tire Machines

  • ISSN: 1195-5228
  • Issued: October 2009
  • Content last reviewed: October 2009

Tires for cars and light trucks can explode with devastating force during inflation or when seating the bead. Workers may sustain critical injuries during the installation of tires on a single piece rim for passenger vehicles.


Rim Clamp style tire mounting machines are extremely popular with tire shops and repair garages because the equipment does not damage or mar the finish on the rim surface during the tire installation. They are available from a number of manufacturers, and come in a broad range of models with a number of accessory options. However, the potential hazard to workers working with or in close proximity to these machines is not widely known.

Certain models of rim clamp tire machines intended for use and sale in Canada DO NOT typically come equipped with pressure limiting or other safety devices. This means that stock machines can be connected to a shop compressor system without a step down regulator to control pressure, making shop air, typically at pressures greater than 690 kilopascals/100 PSI, available to the tire machine's clamp on air fill hose. This particular setup is not fail safe and relies solely on the actions of the worker to ensure that excessive air pressure is not added to a tire during inflation. The worker adds air pressure to the tire via the clamp on air hose controlled by means of a multi-function foot control pedal projecting from the base at the side of the machine. The location of this foot pedal necessitates that the worker be in close proximity to the tire and rim assembly during the most hazardous stages of the operation.


There are two distinct inflation stages of the tire installation that may endanger the safety of a worker if the tire machine and the tire manufacturers recommendations are not followed and the machine is not equipped with an air pressure limiter device. The first stage is when the worker is "Seating the Bead", a process that use blasts of air delivered from the machines accumulator in conjunction with tire inflation through the tire valve stem to seat the bead of the tire onto the rim.

The second stage is during "Air Up", or initial pressurization of the tire. Both stages are distinct but will appear as a seamless operation when the operation is observed.

A worker may be injured using a commonly available "Rim Clamp" style tire machine at either stage of the procedure if a failure occurs in the bead or sidewall structure of the tire which may be facing up or down on the machine's worktable. A failure due to over-inflation with air pressures far exceeding those recommended by both the tire machine and tire manufacturers can produce a catastrophic release of pressure and launch the tire and rim assembly off the tire machine potentially striking the worker and causing serious injury and or death.

Location and Sectors

These machines are commonly found in the automotive service sector but may also be found in other sectors where vehicles are repaired or maintained. Note: The Occupational Health and Safety Act, R.S.O. 1990 c.0.1, Section 25(2)(h) requires an employer to take every precaution reasonable in the circumstances for the protection of a worker. Also, for multi-piece or split rims refer to section 77 of the Industrial Establishments Regulation (Reg. 851), or section 110 of the Construction Projects Regulation(O. Reg. 213/91) for further requirements.

Hazards and Prevention

In most cases, there are no warning signs and no time for a worker to react before a tire and rim assembly fails from any cause during tire inflation or when setting the bead. Workers must be made to recognise the hazards associated with these common tasks and follow the warnings identified both by the machine’s owners/operation manual and by safety warning stickers affixed to each machine. Employers must regard operations involving the mounting of tires on rims as an acute safety hazard to the Health and Safety of any worker.

Action Required

Employers are required to take every precaution reasonable in the circumstances to protect a worker from the hazards associated with the mounting operations. This may include:

  • A-Worker training with strict adherence to the tire machine and the tire manufacturer’s recommended safe operation pressures.
  • B-Pressure Limiter Devices
  • C-Remote Filling Controls in conjunction with physical barriers
  • D-Tire Safety chains, cages, or other protection
  • E-Provide adequate supervision
Standard Model Rim Clamp
Rim Clamp with Additional Safety Features Warning Sign About Over Inflation

It may be difficult to determine if any tire machine is equipped with a “pressure limiter device”. The device is located as an integral internal component of the machine and not readily visible. If you are unsure or unable to determine this fact, the manufacturer, supplier, and/or service technical will need to be contacted.

  • All operators and bystanders should be removed to a safe distance whenever tire inflation takes place.
  • Accelerants or other flammable substance should never be used to set the bead on any tire.

This Ministry of Labour Alert has no legal effect and does not constitute and is not a substitute for legal advice. If you require specific assistance with respect to the interpretation of a legislative provision and its potential application to you please contact your legal counsel.

Remember that while complying with occupational health and safety laws, you are also required to comply with applicable environmental laws.

Please photocopy Ministry of Labour Alerts, distribute them widely and post them where people will see them.