While working on a report about a tire involved in a particularly horrible accident that wiped out a family of four, I speculated about the roles played by the tire dealer and the tire service technician. The retreaded bias tire had been mounted along with a radial tire on the vehicle's rear axle.
The intermixing of tire constructions in this manner is not recommended in the U.S. and is illegal in some European countries.
In addition, the tire's casing had been distorted during the retread curing process. Casing distortion occurs when the size of the built retread is not accurately measured causing it to be cured in a mold having smaller dimensions.
Quite often when this situation occurs, the retreaded tire emerges from the mold looking quite satisfactory. Yet the casing may be distorted to such an extent (as it was in this case) that rapid failure is inevitable.
The tire dealer and the tire fitter have not only a moral duty to the customer-but a legal duty as well. It's not sufficient merely to offer potential customers nothing but a rundown of the available tire brands, types and prices, as many retailers do.
People's lives and well-being are at stake. And merely telling customers about these product options provides them with no advice whatsoever.
Whether he realizes it or not, any retailer who sells a faulty tire is almost certain to wind up later on answering some difficult questions in court.
The fact that this is the world's most litigious society should serve as a warning to tire dealers and tire fitters just as much as tire manufacturers.
No customer should ever leave your premises without having a safe tire on a safe wheel on a safe vehicle.
Those operating even the smallest of dealerships usually possess a lot more tire-related knowledge than the average consumer. There-fore, that knowledge should be freely provided to the customer no matter whether the tire purchased is used, retreaded or new.
This was an accident that never should have been allowed to happen. And it brought a number of questions to mind: Why was the customer allowed to leave the shop with a different-size bias-ply tire mounted on the same axle as a radial? Why didn't the dealer or the tire fitter notice the difference in tire sizes and constructions? Was the tire retailer that hungry to make a sale or just careless?
Just before starting out on his vacation trip, the vehicle's owner had attempted to economize by purchasing a retreaded tire to replace the right rear tire on his Ford Bronco.
Later, while driving along the highway at 65 mph, he had been unaware that the newly purchased tire was disintegrating. Modern vehicle suspensions are so good at isolating the driver from the road surface that he no longer experiences any warning sensation of a flat tire.
In this case, the tire threw off bits and pieces of tread rubber for some distance prior to its sudden deflation. The driver tried frantically to regain control of the vehicle after it oversteered and began to spin. But there was virtually no chance of this as the Bronco careened across the highway and rolled over several times, ejecting its occupants who were not wear-ing seat belts at the time.
The Bronco was equipped with 15-inch, 6JJ wheels, 30x9.5-15 radials on the front axle. The left rear tire was a 10R15 radial. The right rear was the 31x10.5-15 bias-ply retread. This mixture of different tire sizes and constructions had been an invitation to disaster.
The 31x10.5 tire was four years old at the time it was retreaded, after which it later sat in the stock tire rack for two more years before being installed on the Bronco.
Moreover, a prominent circumferential casing buckle was detected in the center of the tread areaand both tire beads were kinked.
Such damage frequently results when the built retread is too large for the curing mold.
Because the casing was buckled, only the central part of the tread made contact with the road surface when the tire was distended by the 35 psi inflation pressure. This led to a severe increase in operating temperature, resulting in a loss of adhesion between the tire body and the tread.
The whole question of mixing tires is a very difficult one and the only simple and completely safe answer is quite uncompromising: All four tires should be of the same type.
This does not mean they merely should all be of radial- or all bias-ply construction-but also of the same make, size and tread design and-if possible-the same age, since shoulder profiles and tread compounds are modified from time to time.
Handling is more a matter of balancing front- and rear-ends rather than controlling the vehicle from one end or the other.
Sudden tire deflation on rear wheels causes severe control difficulties for most drivers. The flat tire soon becomes detached from its rim and thus quite incapable of providing useful braking, tractive or lateral control forces.
The most serious difficulty usually is experienced while the vehicle is cornering with the flat occur-ing on the outside of the curve. As in the case in question, the vehicle commonly is in a passing situation when the loss of control occurs.
Our consumer laws put responsibility on the shoulders of the retailer not to sell goods which place the general public at risk. In every such sale, there is an implied warranty from the seller to the buyer that the goods involved are of salable quality and suitable for the purpose for which they were sold.
The fact that a bias-ply tire was mounted on the same axle as a radial was a contributing factor to the accident, although not the most significant one.
The major problem was that a faulty retread was improperly mounted on a 6JJ rim instead of a 7JJ, which thereby affected the tire's tread contour, causing additional stress and internal heat buildup.
The primary cause of this tragic accident was the sale of the faulty retread tire by the tire dealer.
The tire fitter also was at fault for installing the different-sized bias-ply tire on a narrow rim contrary to the manufacturers' recommendations.
The retreader also shares some of the blame for producing and marketing a defective retread.
All three parties got their ``day in court'' and suffered severe financial penalties as a result.