Big Wheels Keep on Turnin’….
By Jim McCurdy, CEO/Founder – Maine Commercial Tire
And they “roll-on” whether attached to a truck or not. While travelling along our highways watching opposing traffic, we don’t give much thought to dodging a flying wheel assembly. But a recent and heart wrenching tragedy brings wheel-end safety into sharp focus for all of us who perform tire maintenance.
I have spent fifty years in the tire business and have seen and heard of some scary and short-sighted practices. Some examples? I’ve been in many truck garages with no safety cage for tire inflation.
I witnessed a teenage girl sitting on a freshly mounted tire while she held the inflation chuck on the valve stem. In New Bedford I saw the outline of a man’s body in the dust on the ceiling of a truck garage where it had impacted when a tire exploded while he leaned over it.
Tire and wheel assemblies are so commonplace that they are taken for granted by those who move around them. It’s a little-known fact that OSHA requires safety training for anyone who “inflates, deflates, installs, removes or handles” truck tire assemblies.
That means anyone who bolts an assembly to a hub should have documented training!
We all expect the mechanic who is rebuilding an engine to know the torque specifications for attaching a head to a block. There are also very specific torque values to attach a wheel to a hub, but I suspect many who mount wheels do not know the value nor do they understand the danger posed from over-torqueing a wheel stud.
So, what can be done to improve wheel end safety practices? My suggestion is to start from “the outside in” – in other words educate those who least interact with mechanical operations. Drivers, basic level shop employees, people who may not have been schooled in the specifics of wheel attachment requirements. One example is the driver who notices his tire is dramatically underinflated and simply attempts to re-inflate it to 100 psi. This can have disastrous and even fatal consequences. On the professional truck tire service level, we regularly inspect parked fleet vehicles with one of our checks being the condition of the bolt circle. Are there rust streaks indicating potentially loose fasteners? Is the disc face showing cracks? These are things a driver can look for while at a rest stop or a fueler can spot while walking past.
Of course, this approach is “wheel end safety lite”. The other action that should be investigated by truck fleets is the formalized training required by OSHA for those who regularly “inflates, deflates, installs, removes or handles” truck tires. This safety training may be available from tire dealers who offer the TIA (Tire Industry Association) training syllabus. This training can usually be accomplished at the fleet location.
Running a tire at highway speeds while underinflated by as little as twenty pounds can create enough heat in a tire to cause it to separate catastrophically. This will spread tire fragments in the travel lane and may even cause some property damage and downtime, yes…
However, a wheel-off is an entirely different level of safety threat!
Here are some of the causes of a wheel departing a vehicle:
- Incorrect torque (too much is as bad as too little);
- Dirty mating surfaces between the wheel faces;
- Ice on the wheel face;
- Too much paint on the mating surfaces;
- “Previously” stretched studs from too much torque;
- Enlarged bolt holes from previous mis-mounting;
- Low air pressure to the air gun; and the sneaky one,
- Two techs working on the same wheel position, each thinking the other torqued the assembly.
And this doesn’t address the potential for an entire dual assembly to depart the vehicle caused by axle or bearing maintenance issues.
In our business we have had company drivers who, when told their wheel mounting surface is cracked, tell us “just put it back on, we’ll change it back at the shop”. This is seemingly not much to worry about until that moment when it all goes sideways. At best: it’s a few extra hours of downtime. At worst, it results in tragedy, and lawsuits, and sleepless nights, unnecessarily impacting families and draining resources. It may even result in the complete loss of livelihood and ownership of the business.
To answer the obvious question, we usually put a safe used wheel on – at no charge – to get the truck home.
Responsible wheel end maintenance is more than the simple act of bolting a wheel to a hub. It carries with it the weight of respect for your driver, your company and those using the roads your equipment travels over. Irresponsible wheel end maintenance is the same as strapping a 200-pound unguided missile onto the side of your truck and sending it down the road. A mechanic’s error may launch a wheel assembly over the highway divider and into a pine tree, or it may ruin the life of a family.
This is serious business; we all need to do our part.