CSA and Tire Basics

John Baxter | December 01, 2011

Stay out of trouble with the DOT through careful inspections and diligent routine maintenance.

Checking tire pressures with a good gauge will head off citations for low inflation pressure as well as prevent many types of tire damage that net citations.

If you think getting put out of service for an equipment violation is likely to involve DOT inspectors finding something complicated or unexpected, think again. Ten percent of out-of-service violations involve simple tire problems, says Commercial Vehicle Safety Alliance Deputy Executive Director Collin Mooney.

Furthermore, the Compliance, Safety, Accountability enforcement program penalizes carriers’ safety rankings for all violations. Of the 25 most common recorded by inspectors, two involve tires directly and are high-severity-weight violations, carrying 8 out of a possible 10 points. In fact, most tire violations are high-weight infractions. While simple underinflation merits only 3 CSA points, these common violations incur 8 points: running a drive or trailer tire with tread below 2/32 of an inch, running a tire with fabric exposed, and audible leak.

Time weighting means each violation’s weight will be multiplied by three in safety scoring for six months after it occurs. Thus frequent high-weight tire citations, as well as a failure to repair problems, will have immediate negative consequences for you or your carrier’s ranking in Vehicle Maintenance, one of CSA’s seven Behavioral Analysis and Safety Improvement Categories. Potential results are more inspection scrutiny at weigh stations, hassle from your leasing carrier and, ultimately, reduced business.

Bottom line: Do your pretrip inspections consistently. If you have hired drivers, get them to do the same.


Inflation maintenance

Using an inexpensive tread depth device is one way to make sure your tire meets the standard for minimum depth.

Inflation pressure is the most critical part of a pretrip inspection, says Goodyear Marketing Communications Manager Tim Miller. “Proper inflation pressure will help prevent wear and damage, and helps eliminate casing durability concerns. Underinflation may be the cause of much of the visible damage they are looking for in an inspection.”

Running a tire low on air is just as bad as running a diesel engine with low coolant or a clogged radiator. Tires generate tremendous heat when they run because continual flexing is necessary for them to give a smooth ride. Pressurized air creates much of their structural strength and limits that flexing. When the pressure’s too low, flexing – and heat – grow by leaps and bounds. The result is softer, overheated metal cords. When a broken cord pokes through the sidewall, it’s grounds for a citation.

Always use a calibrated inflation gauge to get the necessary accuracy. The old method of thumping a tire doesn’t work, says Curtis Decker, commercial tire product development engineer for Continental Tires.

Guy Walenga, Bridgestone America’s director engineering commercial products and technologies, suggests replacing the valve stem core each time a tire is serviced, and using quality poly-carbonate or steel stem caps with good rubber seals to help retain pressure.

Other aids to pressure maintenance include tire monitoring and automatic inflation systems. They are particularly helpful with maintaining pressure on inside duals. When duals are mismatched because of a pressure difference, it can quickly lead to damage that will yield a citation.


Inspection checklist

Here’s a checklist based on the basic Commercial Vehicle Safety Alliance inspection criteria.

• Eyeball the tires, searching for obvious significant damage to the sidewalls. Especially be alert to tread separation – where there is an obvious crack between the original or recapped tread and the casing. Likewise note any area where cords or fabric are protruding from either the sidewall or the tread itself.

Tread damage (left) and casing damage that exposes fabric (right) do not have to be this severe to merit an out-of-service order.

• Look for significant bulges, Mooney says, often indicative of an approaching failure where cords are broken and forcing the sidewall out. Don’t confuse this with a bulge of fresh rubber vulcanized to the sidewall to seal off a puncture. When these don’t bulge more than 3⁄8 of an inch, they are OK. Some inspectors carry a gauge that can measure them, says Miller.

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