BETTER manufacturing results in better tires. Good tire designs produced with state-of-the-art processes result in exceptional performance, according to Goodyear Tire & Rubber Company. Putting this concept into action, Goodyear has announced a new steering axle tire for heavy trucks built with new manufacturing technology.
Goodyear holds a leading market position for drive and trailer tires, says Ted J Fick, vice-president of Goodyear's commercial tire division. With the introduction of the G395 LHS steering axle tire, Goodyear promises to raise the industry bar for front axle tires, he says.
“Four components make a steer tire perform as it should — tread design, casing integrity, compounding, and manufacturing,” he says. “We feel that we've done a clean sweep in all these areas to provide a steer tire with performance second to none.”
To prove its point, Goodyear says its introductory offer for the G395 LHS provides a no risk challenge. “The steer position is the most critical on the vehicle and that's why this tire comes so highly engineered and tested,” Fick says. “We're more than confident in its ability to perform, and it's why we're offering a no-risk opportunity for buyers to test the G395 LHS for themselves. If the G395 LHS doesn't exceed the verified miles to removal of the customer's current steer tire, we'll retread the G395 LHS free of charge.”
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Everything about the G395 LHS is new from the way it was designed to the way it is manufactured to the actual design, Goodyear says. Conventional tire development is a trial and error process of design, testing, and evaluation followed by more design and testing. Typically, a company goes through three to five design cycles before a new tire is introduced to market, says Joe Zekoski, Goodyear's director of commercial tire technology. Working with technology developed by Sandia National Laboratories in Albuquerque, New Mexico, Goodyear has cut the development process to only two design cycles.
Software from Sandia Labs allowed Goodyear to model tire performance in the early stages of design, a time when conventional processes require that actual tires be built and physically tested. Simulation allowed Goodyear to reduce the number of design options to those most suited to enhancing steering axle tire performance, says Tim Richards, team leader of the advanced engineering team assigned to the G395 LHS project.
Extensive lab testing
Once Goodyear had a physical model of the G395 LHS, it performed extensive tests of the tread designs and of steel belt configurations. Lab tests of the tire footprint shape and pressure provide indications of treadwear characteristics. A procedure called frictional energy analysis uses a high-speed camera to monitor a tire as it rolls across a glass plate. The process looks for tread slip as the tire rolls. Goodyear's FEA results showed lower tread slip from the prototype G395 LHS tires resulting in projections of less shoulder wear and less irregular wear or cupping of tire ribs, Richards said.
The result of all this computer simulation and physical testing is a five-rib design with a tread that evolves in pattern as the tire wears. A new tire has three main ribs with lateral sipes and slots as its primary tread pattern As the original ribs wear, jagged, angled groove walls are exposed across the footprint to help maintain maximum traction and handling characteristics. In addition, the G395 LHS produces a barrel-shaped footprint instead of a conventional rectangular footprint. The traction from this evolving tread pattern allows the tire to remain in use on a steering axle longer, Zekoski said.
The outer ribs of the G395 LHS have a pressure distribution groove with a large radius to reduce pressure build-up. Reduced pressure during cornering improves shoulder wear and reduces the potential for irregular wear and cupping, Zekoski said. All five ribs have edge blades to provide resistance to propagation of river wear.
In addition to enhanced tread design, the G395 LHS is designed to run cool to extend casing life for subsequent retreads. The steel-belted radial tires have four belts with high-tensile steel in the lower three. The top belt is made with polyamide to protect the underlying steel belts from moisture that attacks casing integrity.
New manufacturing technology
To ensure the best performance from the G395 LHS, the tire is built using new manufacturing technology that Goodyear calls IMPACT for integrated manufacturing, precision assembly, cellular technology. The new process minimizes the number of material splices in the tire casing and cuts the number of steps required to build a tire by half. IMPACT is said to increase productivity by 135% and cut cycle time by 70%.
A heavy truck tire such as the G395 LHS is built of 23 separate components that must be assembled by hand prior to final curing, with the result that, although quality control is maintained, every tire is not exactly identical. The new process reduces uncertainty by forming 12 of the components into a single sheet of rubber material. IMPACT uses a hot former to extrude components and bind them together. Sheets from the hot former are fresher than those used in conventional manufacturing with the result that other components adhere better during assembly. In one part of the assembly process the number of splices in the tire is reduced from six to one. All G395 LHS tires will be built at Goodyear's plant in Danville, Virginia, using the IMPACT process.
Initially, the G395 LHS will be available in 11R22.5 and 11R24.5 sizes with G or H load ratings. By the third quarter of 2003, Goodyear will add 295/75R22.5 tires with G and H load ratings and 285/75R24.5 tires with a G load rating. All tires are rated for 75 miles per hour. The G395 LHS is a premium product that will be sold at a premium price roughly 10% higher than the Goodyear G397, which the new tire is intended to replace, said Walt Weller, director of commercial tire marketing.