Wheels may seem like the simplest of components on a car, but the big manufacturers are constantly researching and developing the latest and greatest production techniques and investigating the strongest yet lightest materials to implement into their wheel production processes. Be it Koenigsegg with its full carbonfibre wheels on the Regera or Jaguar reproducing its infinitely cool steelies for the low-drag E-Type, wheels take on huge technical and also aesthetic responsibilities that shouldn’t be taken for granted by us petrolheads. So here’s a quick lowdown of the most popular variants specced on modern cars and how the manufacturers go about producing them.
Steelies are about as basic as wheels can get. Pressed from billets of steel using powerful hydraulic equipment, steel wheels have been standard on most low-cost vehicles for decades and dominated before alloy rims became cheaper to produce. Steel – an alloy of iron and carbon - is a harder metal than most other wheel materials, but this strength brings with it an increase in weight when compared to the likes of aluminium.
The basic way in which steel wheels are produced means that there is very little flexibility when it comes to design or any type of artistic flare. Different sections of a wheel are pressed out and then connected to form the entire wheel, ready to be used once the welds have been sufficiently ground down. This construction means that the only real way different designs can be implemented is to punch holes into the outside face of the wheel, be it for strategic airflow for brake cooling or for some much needed aesthetics.
Most companies will get around the unattractive nature of pressed steel wheels by slapping on a set of hubcaps with some badging to disguise the raw metal and imitate a set of more expensive and stylish alloys.
Alloys until the last decade or so have always been reserved for the uppermost models within a manufacturer’s range, but they can now be specced in pretty much any city hatchback on the market if desired. Based on an aluminium or magnesium construction mixed with Nickel, alloy wheels provide a much lighter package when compared with a steel wheel of the same strength and can be cast in full by pouring molten allow into a pre-made mould.
Unsprung mass is a term you’ve probably come across before; it dictates the mass of components that are not supported by the suspension which includes the suspension components themselves, the brakes and the wheels. A lack of unsprung mass improves handling as it allows the suspension to interact in a controlled fashion with an undulating road surface and deal with the reaction forces from the road surface much more efficiently. This was one main reason why performance cars moved towards alloy wheels, with the lightweight construction helping acceleration and the overall dynamics of a car.
By reducing the amount of nickel within the alloy, a wheel becomes much more pliable and malleable, adding to the design possibilities. This freedom of design has led to some truly spectacular alloy rims over the years, but the softer material also opens the door for some fairly catastrophic results after kerbing…
Most famously manufactured by BBS, wheels can be constructed from either two or three basic components. Two-piece wheels are made up of the wheel face (or centres) and the rim (or barrel), fastened together by rim screws that circulate around the circumference of the wheel centre. A ring of sealant is then applied to the join to further secure the sections together.
Three-piece wheels take it a step further, dividing the wheel rim in two to allow for a degree of adjustability in wheel width. All of this faff makes multi-piece wheels inherently heavier and slightly weaker than single-piece variants, but companies like BBS have developed a ‘rolled rim’ feature that brings the strength levels of its multi-piece wheels up to within reach of even single-piece forged wheels by tempering the once-weaker metal.
Some of the strongest wheels on the market are formed by the art of forging aluminium. This is done by subjecting a billet of material to a ridiculous amount of heat and around 900 bar of pressure, crushing the metal into an extremely dense and immensely strong wheel. The enormous force of compression from the forging makes these wheels extremely light and many times stronger than an equivalent casted wheel.
Countless bargains seem to litter the internet stating high quality replica or reproduction wheels for numerous cars on the market, but one should be extremely wary about going anywhere these tempting nuggets on the web. Although imitation wheels may look the part, they are often made in the cheapest fashion possible to reduce manufacturing costs and therefore lack some essential strengthening processes that OEM wheels undergo.
Most replica wheels are produced using a method called gravity casting which is when the molten metal is poured into a template but not compressed at all and is left to set purely under the pressure of gravity. This means that the alloy is nowhere near as dense as an OEM equivalent which will have had some form of compression forced upon it during the production process. The replica will therefore be lacking in strength and will be far more brittle in comparison, making it a potentially dangerous modification!
With so many other niche types of wheel available, a set of rims can be specced to your each and every need - be it for daily use, the odd track day or even a patch of off-roading now and again. With a vast array of materials and manufacturing techniques available in within wheel production, the perfect combination is sitting out there for you somewhere.
What car comes with your favourite wheels as standard? Do you prefer a subtle steelie or a ricer-spec three-piece rim? Comment below with your thoughts!