HiSpec Wheel & Tire Inc., a Mishawaka, Ind.-based supplier of aluminum and steel wheels to the RV, cargo, marine and specialty trailer industries, said it is offering OEMs “five best practices to prevent dangerous wheel separations and expensive product recalls.”
According to a press release, wheel separations are a serious and potentially fatal occurrence for manufacturers and consumers in the RV and trailer industries, often resulting in multi-million dollar court settlements and expensive, time consuming recalls for manufacturers.
“At HiSpec Wheel and Tire, we continue to innovate and manufacture wheels that exceed the standards set by the Trailer Safety Industry Coalition (TSIC),” states Ron Williams, HiSpec general manager and chief engineer for HiSpec, which produces the Safety Wheel line.
Williams is a former board member of the TSIC and was instrumental in moving forward the new industry safety standards accepted by the National Highway Transportation and Safety Administration (NHTSA) in 2006, at which time NHTSA deemed that wheel joint security is the responsibility of the manufacturer.
The five best practices include:
• Required Thread Engagement: Aluminum wheels are typically thicker than their steel counterparts which can lead to inadequate thread engagement. A ½ inch to 20 inch stud needs a minimum of 10 full threads, or ½ inch, engaged. Remember, the first thread is typically incomplete. The engineers at HiSpec Wheel recommend engagement of 11 full threads or more—all HiSpec wheels exceed this requirement.
• Adequate Lug Nut and Socket Clearance- The torque applied to tighten the wheel is intended to generate clamp load in the studs, however, some of the applied torque is used in friction. Typically there are two torque robbers – one at the thread interface between the nut and the stud and the other at the interface of the conical seat and the nut. Some aluminum wheels have deep lug nut recesses that make it nearly impossible to avoid contact of the socket and the wheel. This adds another factor where friction between the socket and the wheel steal some of the applied torque leaving even less of the torque to generate clamp load in the stud. HiSpec “Clean Line Designs” have addressed this issue to maximize socket clearance and ensure the applied torque goes where it is intended – to generate clamp load
• Proper Torque and Tension Testing On the Assembly Line- Ask your wheel supplier about the clamp loads requirements. Be aware of the torque that should be used with your wheel and lug nut combination. Check this information against the industry standard torque levels needed to achieve adequate clamp load. It may be critical for a field audit from your wheel supplier.
• Component Compatibility- There are often misfits between components. Obtain confirmation from each component manufacturer that its components are appropriate for the application and meet the component guidelines compatible with the other components in the wheel system.
• Compliance with TSIC Recommended Practices- Adhere strictly to TSIC Recommended Practices including the compatibility of components, maintaining clean wheel and hub surfaces, training of personnel and conducting regular wheel audits.