HRE designs, engineers and manufactures wheels using a forging process with aluminum alloy. Because of its manufacturing methods and the materials used, the cost of the wheels HRE creates is very high. As a result, its wheels are relegated to the very high-end of the market, with wheels retailing from $4,500 to $8,000. Porsche owners are the company’s number one demographic; and both companies are intensely focused on performance and quality.

The company’s president, Alan Peltier, joined HRE Performance Wheels as the lead engineer in 1999, and was promoted to president a couple of years ago. Peltier states, “HRE’s philosophy is to make the best wheels in the world, and to provide the best customer service.”

HRE wheels are engineered and manufactured at the company’s facility in San Diego. The wheels begin life as a high quality 7" diameter aluminum billet rod. The billet rod is heated and placed into a precision die where it is pressurized into a raw forging as specified by HRE’s engineers. The result of the forging process is aluminum with a refined crystalline structure where the grain direction is aligned with the primary load direction of the wheel spokes, which strengthens the material.

Peltier explains, “The raw material ends up being about 40 percent stronger than the raw material on a normal cast wheel, and that's very important because we can then take that and use less material to get to the strength requirements that are needed for the vehicle, which gives us a lightweight wheel.”

The raw piece the wheel goes into a lathe which cuts the profile, and then it goes into a mill that cuts out the pattern of the spoke detail. Everything is cut to make it specific for that vehicle—a Ferrari is very different then a Porsche, so all of the details that have to do with attaching the wheel to the vehicle are different. The wheel will get lightly sanded or polished and powder-coated, and then it's done. While most companies make hundreds or thousands of wheels at a time, HRE literally makes four wheels at a time, so all of its business is built to order.

The difference between an HRE wheel and a normal automobile wheel is that standard wheels are generally made from cast aluminum. In comparison to forgings, castings are made by pouring molten aluminum into a mold. This process results in considerably lower strength, ductility, and fatigue resistance.

“This is where Pro/ENGINEER Mechanica comes in,” Peltier explains. “The reason wheels need to be light, is that you want your car to be light. The more weight put on your car, the lower gas mileage you are going to get, the lower performance you are going to get. And, it’s more important on wheels than almost anywhere else because the wheels are part of what they call unsprung mass—that's the wheel, the tire, and the brake—components that are not held up by the suspension.”

“There is another aspect which is called rotational inertia, and this is the distribution of mass about a wheel’s rotational axis. The heavier the wheel, the more rotational inertia it has, and the slower your acceleration is going to be. Your braking distance is going to be longer, because when you slam on the brake, it takes more energy to stop the wheel, and therefore makes your car less efficient and less safe.”

Every HRE wheel design is created utilizing PTC’s state-of-the-art Finite Element Analysis (FEA) to optimize the wheel's strength-to-weight ratio to improve a vehicle's acceleration, braking and handling.

With Pro/ENGINEER Mechanica, design engineers can better understand product performance, and accommodate the digital design accordingly—without needing a specialist’s FEA-background. As a result, engineering gains early product insight, improves verification and validation processes, and delivers higher quality products at lower cost. By gaining early insight into product behavior, companies can vastly improve product quality while saving time, effort and money.

?“Because Mechanica is so integrated with Pro/ENGINEER, I can train guys who are not analysts,” Peltier comments. “I can train designers to use it by giving them a template. It's so easy to use that we can get very, very accurate results with someone who is smart, but not necessarily engrained in the theory. And, I think that's really a powerful aspect of it as well.”

“We started using Pro/ENGINEER Mechanica in 1999, and it is the cornerstone of our wheel development. We just iterate and iterate and iterate and iterate. We run hundreds of FEA analyses for each wheel before we go to prototype. It allows us to really fine-tune the wheel, take mass out of it where it's not needed, put mass in it where it is needed.”

“At HRE, every wheel undergoes countless hours of FEA because half a millimeter or a millimeter difference in cross action matters, a quarter of a degree matters. These tiny amounts make the difference between passing a fatigue test and not, when our engineers are trying to really optimize the wheel and make it lightweight,” Peltier says.

“Pro/ENGINEER Mechanica as invaluable to us. There’s no way we could do without it,” Peltier asserts. “It costs $1,000 for us to test a new wheel model, so it may cost us $3,000 total because we are going to do multiple tests. But if we didn't do it, we would be sending wheels to test, and they would be coming back and they would be failing. So at the end of the day, it would probably cost ten times that much and we would have an inferior product. The product would eventually pass the test through trial and error, but it would be heavier than it needed to be. And, we would probably pay $30,000 per wheel.”

In the United States there are no requirements for testing wheels, just a set of recommendations or guidelines. But, because HRE holds itself to the highest standards, the company adheres to the strict structural standards set by Germany. HRE’s San Diego facility is TüV-certified by a German standards body that comes out to HRE’s facility every two years. HRE believes they are the only aftermarket wheel company in the United States that has done this. The company feels it is essential to validate the engineering design with actual testing, and therefore, HRE wheels are tested to meet or exceed TüV, SAE and JWL standards for strength, fatigue and impact resistance.