Unlike tires and retreads, where there are seemingly endless choices to make regarding tread designs, compounds and performance characteristics, fleets should be able to flip a coin when making a decision on wheels. The original disc wheels were made of steel for the obvious strength, durability and low cost. Then pricier aluminum wheels entered the market so the trucking industry was forced to do some homework in order to justify the extra expense.
Each type of wheel has its own market. Those conscious of weight and image typically gravitate toward aluminum because it's lighter and the finish can be maintained for years. It's also popular on power units as drivers are less likely to complain about vibrations or rusty wheels. But steel remains the choice for most trailers since they often sit unattended in remote yards for days or weeks at a time.
There are a lot of factors to consider when making the decision. Aluminum wheels require regular maintenance if there is any hope for the original finish to survive years of road salt and ice-melting chemicals. And then there's the issue of hand-holes that are available in different numbers, sizes and shapes. The fancy angles and odd shapes look great when the truck is parked, but they can be a nightmare for technicians and drivers attempting to check the inflation pressure, particularly on inside duals. Aluminum wheels also experience something called rim flange wear that resembles cupping on the outer edge of the rim where a wheel weight would attach. This type of wear is natural for heavy or shifting loads, but most drivers will insist the wheel is defective even though there are gauges that technicians can use to determine if the wheel can remain in service.
Appearance has been the No. 1 issue for steel wheels since the beginning of trucking. Even with the best care, rust and corrosion are going to form unless someone looks for and then paints every spot of exposed metal on every wheel. Refinishing has become very popular as the equipment and machinery have become more affordable and seemingly easier to operate. Unfortunately, too many “like new” refinished wheels quickly show signs of rust for a number of reasons, among them a finish coat that is too thin or improperly applied. To make matters worse, solving the problem with a thicker coat can lead to an accident. If the coating exceeds 3.5 mils (the approximate thickness of a magazine page) on the mating surfaces, it will compress after installation and create gaps that lead to loose wheels.
Finally, reputable manufacturers have well-defined warranties that start from the dated stamp on the inside of the wheel. If the wheel does not have a stamp to indicate the manufacturer, the date of manufacture and DOT compliance, then it shouldn't be placed in service. Saving a few dollars on “no-name” wheels may seem like a good idea, but the liability of operating unidentifiable components could have devastating legal consequences.
Regardless of which type of wheel is selected, fleets must recognize that it will eventually need to be replaced. Whether it's aluminum succumbing to rim flange wear or steel that can no longer be refinished, every wheel has a lifecycle. The level of care and maintenance may extend the useful life, but wheels wear out just like every other component on a truck or trailer.