Despite being such a crucial element, wheels are often overlooked when it comes down to getting the most out of your car’s performance. Some car owners are drawn to the aesthetic qualities and huge range of designs that aftermarket alloys can provide, without considering the impact on the end result.
Of course, swapping out your OEM wheels for a nice set of alloys to give your car its own personality and stand out from the pack isn’t necessarily a bad thing - we encourage it! - but if you’re thinking of swapping out the factory-installed set there’s one key area you should pay particular interest in - the weight of your alloys.
Some aftermarket alloys will be much heavier than the OEM parts, and others may be much lighter. Your car’s total weight will impact on the overall performance including acceleration, braking and steering.
To help you out a bit further, here’s a bit more detail in how the weight of your car is distributed.
Sprung Weight - the total weight of the components of your car supported by your suspension. This could include the chassis, engine and gearbox, for example.
Un-sprung Weight - all of the parts that are not supported by the suspension system. This could include axles, suspension components, tires and, crucially, wheels. It’s the unsprung weight that has the most impact on how your car performs and by reducing the load you can experience much better handling and response on the road.
Rotational Weight - usually refers to any component that rotates such as drive shaft, wheels and tires. By decreasing the weight of these parts you can reduce the amount of energy required in acceleration and deceleration, providing much more efficient performance.
So if speed and performance are what you’re after, then make sure you opt for lightweight wheels.
The difference between Cast, Forged and HLT Wheels
Deciding on a new set of aftermarket alloy wheels has become decidedly trickier over the years. The variety of options on the market have grown substantially thanks to improved production processes that meet the needs of just about every driver, including stronger wheels with less mass for performance and racing.
There are three common manufacturing processes for the aftermarket MINI wheels we sell at Lohen; casting, forging and High Light Technology (HLT) which are all much lighter than the OEM wheels. To help you decide which would be the best fit for your vehicle, we’ll explore them in more detail.
Cast alloys
Casting aluminium wheels is the most common and least expensive process of manufacturing alloy wheels on the market. The “casting” occurs by melting aluminium alloy into a mould, which provides the overall shape of the wheel before it’s cooled and finalised into the end product.
Although they generally tend to be inexpensive and easy to obtain, cast alloys are notorious for cracking which is often irreparable. Additionally, because the manufacturing process requires extra material to strengthen the wheel, cast alloys tend to be much heavier, which means they’re not overly suited for track days or race use.
If you use your MINI just for day to day use or town driving, replacing your OEM wheels with cast alloys can be a relatively cheap way of improving the look. However, if you’re after improved performance and overall reliability then you may need to look elsewhere.
Forged alloys
At the other end of the spectrum, forged wheels are stronger and lighter than cast wheels but may set you back in terms of budget. The savings in mass, start in the production process, where aluminium is forged rather than poured into a mould, leading to around 30-35% less material being used.
The end result is a wheel that has greater strength and resistance as well as being able to withstand impact and high levels of load stress on the road and the track. They’re also far more suited to performance and racing as forged wheels can withstand the load of lower treadwear tyres such as slicks.
Although sturdier than cast alloys, they’re not indestructible. If the alloy is damaged it can bend or become dented and whilst this can be repaired, it’s not always the case. For performance and overall reliability, forged alloys tend to have the edge overcast, just be prepared to shell out a bit more for the privilege.
HLT (High Light Technology)
As well as cast and forged wheels some manufacturers have created their own manufacturing processes to take crafting to the next level and improve weight reduction without compromising structural strength.
OZ Racing is one of these manufacturers and their High Light Technology (HLT) has been developed as a direct result of their experience with Formula 1 and other professional motorsports.
HLT is essentially a heated spun flow-forming process which focuses on improving the characteristics of the wheel that provide the reduction in weight and amp up the structural integrity to give a more reliable product that can pass even the toughest of safety measures.
How it’s made
HLT is a three-step process, which leans heavily on solutions in professional motor racing and the latest engineering techniques.
Firstly, the as-cast alloy to be used in HLT (A) is positioned onto a flow-florming mould (B) where it is then heated to a high temperature and rotated at high speed.
Whilst at temperature at being rotated, a special disk presses on the barrel which stretches it to the desired profile and thickness (C).
Due to the stretching process, the end result is a wheel that has a lot in common with a forged wheel, in terms of reduction in weight and improved strength, but with improved resilience and capacity to withstand more elastic deformation energy.
Performance Benefits of a Lightweight Wheel
As a MINI is already a small and lightweight car, any changes to its overall mass will undoubtedly have repercussions in terms of overall performance. This does not just relate to acceleration and top speed but down to handling and responsiveness at the wheel too.
Choosing a lightweight alloy wheel will provide a reduction in rotational mass, which as we mentioned before are the components of the car that rotate such as tyres and wheels. By lowering the rotational mass, you don’t need as much energy to power them leading to improved performance in acceleration and deceleration.
Alloy wheels transmit less strain to your suspension springs and axle, and as such they allow your car to follow the road more comfortably. This gives you a better grip on the road surface and improves your handling and steering.
Another benefit of the lighter weight that alloy wheels provide is that they’re kinder to your fuel tank. As the car will be transporting less weight, your fuel consumption will reduce giving you an improved MPG, even if it’s just a marginal gain.
Essential measurements when buying a wheel for your MINI
To make sure you’re ordering the right wheel for your MINI, there are some essential measurements and terminology that you need to be aware of. This will make sure that you select the correct alloys for your vehicle, and reduce the risk of damaging your car with incompatible fitments.
Diameter - the diameter of a wheel is the width across the centre, usually measured in inches. MINIs such as the R53 or R56 usually have either 16” or 17” diameter wheels, whilst the F56 will have 17” or 18”.
ET (mm) - the offset refers to the measurement between the central line of the alloy to the mounting face. It’s crucial to get the ET correct as this will take into account space to accommodate brake calipers and provide sufficient structural support.
- Zero offset - this means the hub is even with the centre line of the wheel
- Positive offset - the hub is forward of the centre line towards the ‘front’ of the wheel
- Negative offset - the hub is closer to the ‘back’ or brake side of the wheel An alloy with an offset either way can start to impact on the durability of the suspension and cause issues with performance.
PCD (mm) - stands for Pitch Circle Diameter and consists of two numbers - one to indicate the number of mounting holes on the wheel and the second to measure the diameter of the holes in millimetres. A MINI R53 or R56 requires a PCD of 4 x 100, and R60 will require 5 x 120 and F56 will require 5 x 112.
TPMS - stands for ‘Tyre Pressure Monitor Sensor’. This indicates that the wheel supports locations for tyre pressure monitors, which alerts the driver when your tyre pressure becomes too low.
Summary
Improving your car’s performance is all about marginal gains and improving each area methodically without impacting on another. You don’t want to waste your efforts re-mapping and improving your engine output by swapping out your OEM wheels for the wrong aftermarket alloy.
Where possible, try and replace the alloy with either the same or lighter weight, which should give you an overall improvement in performance. By going heavier, you’re running the risk of putting extra strain on your suspension system and reducing the overall handling.
At Lohen, we offer plenty of options for lightweight alloys for MINIs from leading brands:
Sparco - Part of the OZ family these cast wheels offer awesome designs and great value prices.
OZ Racing - Italian based with years of experience in a wide range of aftermarket alloys for road and track
Team Dynamics - lightweight, durable and affordable many Team Dynamics models can be created with custom offsets
TWS Forged - a fast-growing Japanese brand who are making strides with their super lightweight and reliable forged wheels
BBS - Originating from Japan, this historic brand offers some of the most iconic wheel designs on the market in both forged and cast manufacturing processes.
Click here to shop for MINI wheels at Lohen - Gen 1 / Gen 2 / Gen 3
For more help contact our expert team on 01785 859999 or [email protected]
