NEW ORLEANS-Californians Dan Harper and Bradford Boulais are inventors of a device they hope will prevent deaths and injuries due to the mismatching of 16-inch tires and 16.5-inch rims. Their invention is an easy-to-use, half-moon-shaped gauge that fits-or doesn't fit-over a rim's bead-seat area to determine whether it's the proper size for safely mounting a 16-inch light truck tire.
``You simply lay the gauge on the lip of the rim and then slide it forward,'' explained Mr. Harper of Poway, Calif.-based Tire Safety Engineering, the company formed to market the tool.
If the gauge slides all the way onto the rim, it's a 16-inch rim, explained Mr. Harper, a regional tire center manager in San Diego for Price/Costco Inc.
However, if the gauge is placed on the lip of the rim, but isn't wide enough to slide over it, the rim is larger than 16 inches-and no attempt should be made to fit it with a 16-inch tire, he continued.
In the case of a 16.5-inch rim, there will be a gap of 1.5 inches between the tool's center and the rim seat, added Mr. Harper, who co-developed the gauge after encountering the 16/16.5 mismatching problem in the warehouse club's tire centers.
The two rim sizes are close enough in appearance that confusion can and does occur-sometimes with disastrous consequences for those nearby. When the tortured beads of a 16-inch tire shatter, it can ``explode'' with such force the blast can hurl a 170-pound man 60 feet into the air.
Tire and rim makers began phasing out their 16.5-inch products as far back as 1979. But since the average life span of a wheel is 20 years, many remain in use.
Enough are in service, in fact, to have figured in more than 250 lawsuits involving accidents said to have occurred when 16-inch tires were mistakenly fitted to 16.5-inch rims.
Most tire makers began beefing up the bead wires in 16-inch tires as early as 1983 to reduce the likelihood of such explosions. However, some early-generation 16-inch tires, made before the changeover to the so-called ``safety beads,'' probably are still in use-particularly those that saw initial service as spares on pickups and other light trucks.
One source, the Washington, D.C.-based Institute for Injury Reduction, a consumer advocacy group that in 1991 lobbied unsuccessfully for a government recall of 16.5-inch rims, has estimated as many as 30 million tires lacking such beads remain in service.
Frustrated over the ineffectiveness of industry safety procedures designed to protect tire service workers from injuries resulting from such mismatching accidents, Mr. Harper enlisted the help of Mr. Boulais, an aerospace engineer, in solving the problem.
After considerable research and experimentation, the pair came up with their ``16-inch Rim Gauge.'' The tool is designed to provide a two-second, ``go'' or ``no-go'' visual check for verifying that the rim is the proper 16-inch size-even under adverse lighting or other conditions that make identification by other methods often difficult.
These methods include looking for the size designation as imprinted on the sometimes less than pristine rim surface or examining by eyeballing or feeling the lip of the rim to detect the difference between the 5-degree taper of the 16-inch and the 15-degree taper of the 16.5-inch rim.
After researching the various procedures recommended in the industry for identifying 16- and 16.5-inch rims, the two concluded that measuring the bead seat area was the only reliable method for determining a rim's size.
``So we set about designing a tool to measure that area,'' said Mr. Boulais, adding that special effort was made to reduce or eliminate the chance of human error in the measuring process.
Mr. Harper said Price/Costco already is using the gauge in its tire centers and Sears, Roebuck and Co. also is evaluating it. Meanwhile, the two inventors are hoping to get additional national distribution for their product.
The gauge comes as part of a kit that retails for $69.95 and includes a poster warning of the dangers of mismatching 16- and 16.5-inch tires and rims and advising workers to check the rim size before installing a tire.
Also included is a written set of training procedures (designed to be signed by the employee and kept on file), plus a hook for hanging the tool on the tire-changing machine within easy reach.
For more information, contact: Tire Safety Engineering, Dept. TB, 13351 Cree Drive, Poway, Calif. 92064; (800) 319-3131 or (619) 683-9021. Fax: (805) 544-4381.