Do Lightweight Wheels Matter?
As long as there are people, there will be differences of opinions. What began as a simple idea for this week’s article turned into a rabbit hole thanks to the information that was gathered to write it. The topic in question was if lightweight wheels are something from which a BMW enthusiast can benefit. What we found was there seem to be a few schools of thought that depend greatly on the driver and how the car is used. This week, we’re going to address what lightweight wheels do and how you can possibly benefit from them.
First, the burning question: do lightweight wheels make a difference for my BMW? The answer is, truthfully, both yes and no. To the enthusiast who never spends time on the track, or does not compete on one, the answer is ‘no.’ However, if you are beginning to reach the limits of what your car can do in stock form as you better your driving, then wheels absolutely make a difference, but there are some caveats to that answer.
Like we said if you don’t race and don’t plan to, buying wheels should solely rest on your preferences for quality, durability, fitment, and style. Other than those factors, you shouldn’t worry too much. That doesn’t exclude you from considering a lightweight wheel like APEX, as they are intended for BMW fitment and are excellent quality, but it does mean you don’t need to make up your mind on a wheel solely based on numbers. If you like the style, fitment, and manufacturer, go for it! |
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However, if you are concerned with racing and you are looking for ways to make improvements now that you have reached the limit of your stock car, lightweight wheels are a great place to start. Notice we said ‘to start.’ The benefit of lightweight wheels is measurable, but not exactly consequential alone.
A wheel’s effect on handling, braking, and acceleration is the result of its weight. While not exactly a huge contributor to the overall characteristics of the car’s performance, they represent one of several components or systems that are ‘parasitic’ to the horsepower available at the engine. What could be called ‘drivetrain loss’ is thanks to the rotational mass of everything that transfers energy, or horsepower, to the ground. The crankshaft, flywheel, gears, driveshaft, diff, wheels, axles, and brake rotors all transfer that energy by being driven by the engine. The more work the engine has to do to spin all those parts, or the more they resist a change in RPM, the less responsive they will be and more power will be ‘lost’ to turning them. |
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If you want to improve your power output, it will take small steps that add up to reach your goal. Lowering the rotating mass of your wheels is one small step you can make. The use of lightweight pulleys, flywheels, brake rotors, wheels, driveshafts, and even your wheel bolts all stem from chasing a more efficient delivery of power with more responsiveness.
With wheels like APEX or BBS Motorsport, you are shaving weight that is significant when added together and considered as unsprung, rotational weight. By reducing wheel weights, even by just two or three pounds a wheel, the total is added and then multiplied as it affects the total ‘weight’ of the car. Though they don’t actually lower the weight by multiple times their actual weight, they do make it feel that way since they take less energy to turn. |
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| Not only does the weight-saving play a part in a bigger whole picture for performance, but it also has a marginal effect on the brakes. It does not, technically, affect how quickly a car brakes, but the lower weight rotating means the brakes won’t fade or wear quite as quickly. It may not be noticeable at all on a street car, but it can make a slight difference to a track vehicle that is looking for that kind of marginal edge. In a situation where milliseconds count, that extra bump can be a huge difference. However, it would be difficult to really feel that difference. |
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| That leaves us sort of where we began. The need for lightweight wheels and other parts are definitely beneficial, especially for cars that see track time. If you are a competitive driver who has reached the limits of what their car can do, lowering the rotating mass being driven by your car with lightweight wheels and more is incredibly effective. If you are an enthusiast who does not intend to compete, there are still those benefits available, but they shouldn’t exclude a wheel strictly based on weight. So, we are left with two technically correct answers. Yes, lightweight wheels make a difference, but only to certain drivers. | |
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