Since being rolled out by the Ancient Greeks in around 3500 BC, the wheel has been constantly re-invented. Today, the main innovations centre on producing larger, brighter and cheaper wheels. Matthew Beecham reports.
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For some time, aluminium (alloy) road wheels have been the most popular material of choice by the OEMs, recognising both the weight efficiencies of aluminium and its visual appeal.
According to the American Iron and Steel Institute (AISI), however, steel wheels are making a comeback as vehicle makers realize they can save up to US$250 per vehicle, without sacrificing quality or performance. AISI’s member companies represent about 75% of both the US and North American steel capacity.
“Our objective is to return steel wheels to 60% [fitment rates],” said Jim Cran, project manager, AISI. “At one time, steel was 100% but then slipped down to 40%. We are now seeing steel wheels rebounding. We feel that the aluminium wheel market has matured to the extent that it is losing market share. So our activity is basically about convincing the OEMs that they can make higher margins using steel wheels. In fact, we believe that they can increase their margin by up to US$250 per vehicle if they use steel wheels.
“Our market research has conclusively shown that consumers do not buy a wheel based on material. They buy it based on appearance. But in many cases the consumer does not have a choice. The way cars are marketed in North America means that the base [entry level] car comes with a certain wheel. If the consumer then looks at options, the consumer is faced with various upgrade packages. The OEMs include higher and higher styled wheels as you go further up the upgrade package chain. So the consumer thinks he or she is receiving more value in an upgrade package even though the wheels are just one of ten or so items in that package.”
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By GlobalData“The OEMs have traditionally had the perception that consumers prefer an aluminium wheel over a steel wheel and would accept aluminium wheels if included in an upgrade package. Of course, the OEMs’ objective is to make a higher margin by putting aluminium wheels in an upgrade package. Our consumer research shows that consumers are reluctant to pay extra for aluminium wheels on their own. So we had to show the OEMs that consumers don’t buy aluminium or steel wheels but buy a good-looking wheel. We also had to show them how to style steel wheels in such a way that they are equal in appearance to an aluminium wheel. Doing so would allow them to use steel wheels in their upgrade packages and obtain a higher margin — between US$100 and US$250 per vehicle — depending on the aluminium wheel being replaced.”
“Steel wheels are more durable than cast aluminium,” added Keith Pope, manager, Industrial Design, McKechnie Vehicle Components. “The manufacturing processes for steel wheels are well known now. We have reached the point where the general public would be hard pressed to tell the difference between a steel wheel and an aluminium wheel from its appearance. At the end of the day, the consumer is not interested in what their vehicle’s wheels are made from as long as it makes it look better.” US-based McKechnie Vehicle Components, a division of the McKechnie Group, designs and produces wheel trim, plastic and steel claddings and metal wheel trim parts.
“The overall trend is toward more aggressive wheel styles,” said Eduardo Mikami, product engineer, Light Vehicle Systems – Wheels, ArvinMeritor Inc. “The OEMs are challenging us to offer the same styling on steel wheels as that typically found on alloys. Our response to that was the super spoke wheel which mimics the thin spokes of the aluminium wheel using steel. Thanks to high strength steels, this design offers a far more cost-effective solution to producing a highly ventilated wheel.” ArvinMeritor is a major producer of steel wheels for the light vehicle OEM market, principally in North and South America.
The AISI claims that DaimlerChrysler, Ford and GM and a number of Asian and European carmakers, are changing back to steel wheels for base wheels as well as for upgrade packages. Among the reasons for steel’s comeback, says the AISI, are better steel and better wheels. New steels include micro-alloy HSLA, dual-phase and Bainitic steels which are high-strength and advanced high-strength steels.
ArvinMeritor says that simulation software has greatly improved over the last few years, allowing for far more precise designs. “We make good use of simulation software to examine the stress level behaviour of a wheel under the certain loading conditions specified by our customers,” added Mikami. “In doing so, we can change the profile, material grade and thickness of the wheel in just a few clicks of a mouse. Also, every time we design and produce a wheel, we feed back the results to our database. So year after year, our analysis becomes more precise. We also use stamping simulation tools. That means our experts can design a tool and then test it virtually on a computer. That saves us time and money.”
Figure 1
Wheel appeal: ArvinMeritor designs and produces a variety of wheels, including styled drop centre wheels, cladded and painted integrated wheels and super spoke with wheel cover
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Source: ArvinMeritor
Are steel wheels really making a comeback? Although the aluminium wheel market continues to grow, we could soon see it beginning to plateau. Steel wheels certainly continue to maintain their position in the truck market, with aluminium representing only 10%-12%. However, Accuride sees the market swinging in favour of aluminium. “Americans see two basic reasons to buy an aluminium wheel instead of a steel wheel: aesthetics and weight,” said Mike Blacker, corporate director, marketing and product development, Accuride Aluminium Wheels. “Heavy truckers look for aesthetics in their wheels. They also look for weight savings. For instance, a standard steel wheel for a heavy truck typically weighs about 76 pounds compared to one of our standard aluminium wheels weighing just 47 pounds. So if they fit ten aluminium wheels to their truck, there is quite a bit of weight they can take out. That in turn can give them an improvement in fuel consumption and payload. That said, our Lightweight Steel Wheel uses a higher strength alloy and weighs 66 pounds. So if someone is looking to get some weight savings but doesn’t want to pay the premium for aluminium then here is a product that straddles two markets.” Accuride produces wheels for heavy- and medium-duty trucks and commercial trailers. The company also produces wheels for buses, commercial light trucks, pick-up trucks, SUVs and vans, sold under the Accuride brand.
Other trends in wheel design include larger diameter wheels. There are two main reasons for that. The first is appearance; people like the highly styled wheels with low profile tyres. There has been a steady tendency, during the last 10-15 years, for cars to be fitted with wheels which are both larger in diameter and wider than those seen in cars of 1990 and earlier. At that time, the average wheel rim diameter was around 13-inches for B/C segment products, increasing to 15- or 16-inches for high-end and luxury models. Today the equivalent figures are 15- to 16-inches in the C-segment and up to 20-inches in luxury models. While there is some advantage in a larger-diameter wheel, which reacts less sharply to road surface bumps and craters, in most cases the increase has been for cosmetic purposes. In the same way, wheels (and tyres) have increased substantially in width. Again, this has usually been for cosmetic rather than chassis engineering purposes. Although larger wheels are a mixed blessing for chassis engineers, they are welcomed by brake engineers as they offer more space for larger discs.
The North American market is also said to have more of an appetite for brighter finished wheels than in Europe. Another styling trend emerging in the US is for wheels resembling a three-dimensional look, as an auto executive told us, “In the past, wheels tended to look ‘flat’ with holes in them. Over the past two or three years, we’re seeing a more 3D look, meaning more of a sculptured surface with deeper spokes. That’s happening on cars as well as trucks.”
In observing hub cap trends in the North American market, Pope said: “The trends continue to centre on a bright or chrome plated appearance together with a high indication of chrome plated surfaces. Hub caps are still leaning towards plastic and painted surfaces while stainless steel wheel covers have almost disappeared.”
So who really determines wheel ornamentation? Is it the OEM, car dealer or the consumer? Pope added, “In my opinion, the regional car dealer will order from the car manufacturer what they think will sell in their area. So when a consumer looks round a new vehicle, they basically look for the prettiest package that they can get for the best price. So I think that the person at that dealership is the one who influences demand.”
In the final analysis, price pressure is still the dominant issue for wheel makers, as an auto executive said: “In this business, you no longer get credit for quality, delivery, reputation, confidence or customer service. None of that matters these days. What matters to the OEM is price. If you can’t meet the price, the OEM will source from someone else.”
