by Iris Winston

Taking Precautions

If you own a vehicle with an externally mounted spare tire, take precautions to ensure your spare is secure.

The first step is to contact a car dealership, says Doug Mayhew, Public Relations Manager, Canadian Automobile Association, Northern and Eastern Ontario, provide the vehicle’s identification number (VIN) and so “ensure that nothing is amiss with your vehicle.”

Step number two is to follow the dealer’s recommendations, which are likely to include routine checks and lubrication of the spare tire mount.

“Having a spare tire that is usable is part of safe motoring,” says Mr. Mayhew, pointing out that the underside mounted spares are in an inconvenient location for checking whether they contain sufficient air and are more likely to rust.

“No matter what type of device is used (for the mounts), waste material from the road collects,” he says. “The result is that many motorists are incapable of releasing their own spares when they need them.”

For the driver following a vehicle with an externally mounted spare, Mr. Mayhew offers one of the basic rules of safe driving.

“Follow at a safe distance and be prepared to stop,” he says.

A spare suddenly released because the mechanism holding it breaks is “going to spin, bounce and roll, so the last thing you need is to be too close or going too fast and having to slam on the brakes.”

Externally stowed spare tires are dangerous to your driving health. They are also a safety hazard for the drivers of other vehicles who may suddenly be faced with free-wheeling tires heading towards them on busy roads.

Since 1993, Transport Canada’s Motor Vehicle Regulation Branch has received close to 400 complaints about spare tires dropping from their cradles under light trucks, mini-vans and sports utility vehicles manufactured by Chrysler, Ford, General Motors and Toyota, notes Chief of Defect Investigations and Road Safety Lars Eif. Several accidents, including two injuries, have been attributed to breakaway spare tires and restraints. (The National Highway Traffic Safety Administration in the US records similar problems with externally mounted spare tires.)

The practice of mounting the spares outside these vehicle types was intended to make interiors more spacious. Certainly, the design feature fulfilled that objective and, as an added benefit, kept the interior floor flat. However, it opened the way to a much more serious problem than passengers being a little cramped or storage space being reduced.

“The externally stowed spare tires and spare tire restraints are a particular problem when steel cable is used,” says Mr. Eif, explaining that the failure modes differ, depending on whether galvanized or stainless steel cables are used to hold the tires in place.

Galvanized steel is subject to corrosion. Particularly in Eastern Canada, where salt is used extensively to de-ice roads during the winter months, the strands of the galvanized steel tire restraints, used primarily on 1984 to 1988 vehicle models, are eaten away by the salt over the years. The spare tire and winch assembly of a six or seven-year-old vehicle may be held in place by just one or two remaining strands of cable. A jolt on the journey, the last thread breaks, the spare tire drops to the highway and careens towards the drivers behind.

By 1993, most manufacturers had licked the corrosion problem by using stainless steel for their spare tire restraints. This did not mean that the spares were entirely secure, however.

Stainless steel has some flexibility. Any movement of the tire bouncing against the cable while the vehicle was in motion contributed to metal fatigue. The constant flexing can eventually lead to the loss of both the tire and the winch assembly.

In 1997, the Canadian Automobile Association issued a warning to owners of mini-vans, pick-ups and sports utility vehicles with spare tires held in place by a winch and cable system on the underside of the vehicles noting that “the tire may come loose while the vehicle is in motion.” The CAA suggested that motorists should check the assembly as part of the regular winter tune-up to “ensure that the cable and winch are not corroded. If they are not corroded, they should be greased. Even if the spare wheel is attached with a threaded bolt, it should be lubricated to ensure access in an emergency.”

Apart from the damage to the driver’s vehicle resulting from his driving over his own spare, ripping rubber and bending rims, loose tires and rims are accidents waiting to happen to the automobiles behind. In 1997, two people were injured when a flying spare hit the windshield of their car, for example.

A couple in their 70s were driving their four-door sedan behind a pick-up truck when it lost its spare. The driver of the passenger vehicle lost control of his vehicle when the wheel struck his windshield and ran off the road near Wawa, Ontario. Both were taken to hospital with minor injuries. They were released later the same day.

“Transport Canada regards winch tire cable failures and spare tire separation as a safety issue and talks with vehicle manufacturers are in progress,” says Mr. Eif. “They are well aware of the hazards and are considering what to do with older fleets. They are still using stainless steel, but are working on redesign.”

The problem is tapering off somewhat, adds Mr. Eif, as the externally mounted spares in the worst cases have already fallen off. However, Transport Canada continues to “prod” the manufacturers because of continuing concern about the dangers posed by the breaking and loosening of the cable/winch mechanisms.

To date, no car manufacturer has recalled vehicles employing this design. Canadian legislation does not permit Transport Canada to order a recall. The department’s Motor Vehicle Defects Branch negotiates and encourages best practices among manufacturers, but is not set up to be an enforcer.

“We are cooperating fully with Transport Canada on this issue,” says John Arnone of the Ford Motor Company of Canada. “The number of failures on Ford vehicles is minimal at 94 – and this covers Aerostar, F-Series pick-up and Econoline with some models going back to the 1986 model year. We are unaware of any crashes or injuries that have occurred as a result of spare tires dislodging from Ford vehicles.”

Stew Low, Director of Public Relations of General Motors of Canada, who says that GM vehicles have had very few problems related to this issue, notes that “the winch/cable mechanism is pretty well standard across the industry and problems appear to be maintenance related.”

Maintenance involves regular inspection and lubrication – both difficult to accomplish because of the position of the spares.

To date, says Mr. Eif, Chrysler is the only auto manufacturer to have installed a secondary latch on the spare tire restraint (in vehicles model year 1996 and later), so that even if metal fatigue weakens the stainless steel cables, the winch mechanism is still held in place. Mike St. Pierre of Chrysler Canada Ltd. confirms that the secondary latch appears to have resolved any problem in Chrysler products related to underside mounted spare tires.

The issue does not affect passenger vehicles as their spares are stowed inside.

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