SEMA Member News—March/April 2011
Standards for Making Safer Wheels
SEMA and the WTC strongly support J2530 and urge manufacturers to adopt its recommended practices.
“Consumer safety was the driving force in the development of these guidelines,” said George Finch of Carlisle Tire and Wheel and WTC’s science and technology chairman. “It’s a way for manufacturers who care about safety to differentiate themselves.”
Three test machines are required for the SAE J2530 radial fatigue, cornering fatigue and impact fatigue tests. They are designed to fatigue all of the metal components and design features of an individual wheel.
The radial test fatigues the metal in the rim flanges of the wheel, the section that holds the tire onto the wheel and is loaded through the radial axis of the centerline of the wheel. This test also fatigues the metal in the spoke features of the wheel, which carries the load of the vehicle from the hub to the center disc and then to the barrel of the wheel. With every revolution of the wheel, the components are compressed under load as the test load passes over the tire footprint load point and then relaxes after the load has passed. This movement fatigues the metal through the wheel as if it were mounted on the vehicle.
The cornering test (a.k.a. rotary fatigue) fatigues the metal in the hub and the center disc as it pertains to the mounting pattern all the way out to the connection points of the barrel part of the wheel. This is the most stringent of the three tests, as it exercises the portions of the wheel that are subjected to the most movement under load. This test represents the wheels that steer a vehicle and simulates a cornering maneuver, the point at which wheels are subjected to the greatest
The lateral curb impact is designed to simulate hitting a curb and causing a shock injury to the wheel from the side. The applied impact energy determines if the wheel can sustain an injury from a side impact and not break or crack the rim flange, causing air loss to the tire. This immediate burst of energy can also cause the mounting pattern or center disc to crack, break or separate.
These three tests are staples for benchmark testing in the wheel industry. If any wheel has a design flaw or a material weakness, it will be presented and found during these tests. The SAE and WTC have done a great job in developing this testing standard to establish a set of industry-recommended minimum guidelines for the wheel industry.
SAE is considering taking an additional step, requiring manufacturers to register with the organization in order to place an SAE logo on wheels that conform to J2530. The voluntary program would provide consumers with access to a database of participating companies and basic test results. SAE intends to eventually expand the program to require that participating companies submit test results to SAE for publication and require that individual test labs be certified using SAE-recognized procedures in order for those using the recommended practice to claim individual certification to
SEMA and WTC have expressed reservations about the registration/certification program.
“We are a self-policing industry, and there should be the means to provide some oversight in our industry,” said Tim Dietz of Standards Testing Laboratories Inc. and WTC’s chairman. “SAE J2530 testing practices help provide the tools with which a company might ensure that it is producing a safe product that will perform in the field as expected. However, there are companies that already test their products and others that still do not. We are not entirely convinced that this portion of the SAE program will solve this problem. We feel that this program will only affect those companies that are already performing the testing and will not reach those companies that are not testing. As this program progresses, we hope to find ways of prompting the manufacturers that do not legitimately test their products without adding unnecessary overhead to burden those responsible manufacturers that already do conduct testing.”
SEMA and WTC continue to support the J2530 standard and are actively working with SAE to address the industry’s concerns and create a program that benefits all.