Size Matters!
One of the first considerations when selecting alloy wheels is the size. The size of the wheels significantly influences the overall look of the vehicle.
Usually, the first thing people think about when choosing a set of wheels is the style of wheel. The second thing tends to be the actual size of the wheels. In more recent times, wheel sizes have been getting larger, and often sizes that were considered to be a big wheel in the past are pretty much an average size now. In some cases, those wheels might even be considered small.
Harping back a few years, VW Golf GTI and Ford Fiesta XR2 drivers loved to upgrade to a 15-inch wheel from the standard 14-inch OEM wheel (Plus One Sizing). A 15-inch wheel now you will usually only see on small cars like a Fiat 500 or similar. Even the Vauxhall Corsa leaves the factory with a 17-inch rim.
So is bigger always better? Hmmm. Not always.
Fitting larger Alloy Wheels - Plus Sizing
The classic way to make your car look better is to get bigger rims. But how much bigger? The most common upgrade is usually Plus Size One (e.g. from the 17-inch original to 18-inch aftermarket wheels). This normally doesn’t cause any fitment problems with the majority of cars. Problems can be, say, the tyre scrubbing on the wheel arch or against suspension components on the inner side.
In some cases, some cars lend themselves to extensive modification. For example, cars such as the Nissan Skyline, people fit larger staggered width (wider rear) wheels without any issues. The standard car comes on 16×6.5″ wheels as standard, with a 205/55/16 size tyre all-round. One example had 17×8.5″ Front wheels (1-inch diameter larger and 2 inches wider). Rear wheels were 17×9.5, so 1-inch diameter larger and 3 inches wider, with no modification to arches at all, no spacers needed!
Whether it’s a GT car, a Touring Car, or a Tarmac Rally Car, it is not often you will find a high-performance road car that doesn’t feature bigger rims. Whether you have a high-performance car or not, keeping rolling radius similar makes sense if the car is used on the road a lot.
In a nutshell, you need the circumference of the outside of your tyre, to be more or less the same as it is as standard. So, the basic premise is, you’re just changing the diameter of the rim and making the tyre height smaller to compensate.
If your rolling radius ends up larger than as standard, the speedo will under-read. If your licence is important to you, best not to introduce too much error here, as you will likely end up speeding more often. A larger rolling radius could reduce the acceleration of your car as the overall gearing would be higher. Top speed could potentially be increased however though, (depending on the car). Unless you lower the suspension at the same time, making the rolling radius larger will make the car sit higher.
Fitting smaller Alloy Wheels - Minus Sizing
Larger rims have always been more popular than smaller rims, but at times, there are advantages to using smaller wheels too. A large alloy wheel might typically have skinny low profile tyres fitted. A smaller rim, however, can usually use a higher profile one which is more comfortable on road.
For ultimate lows, smaller aftermarket alloy wheels usually do the trick. The smaller the wheel, the lower the car actually goes. If you want your car ‘slammed’ on the deck, this is the way to go usually. A typical example of a vehicle modified in this way are VWs Camper vans. You could have the opposite problem to making it larger if you make the rolling radius smaller. The car will be lower, which may cause ground clearance issues (even more so with lowered suspension). Your speedometer will over-read, which isn’t as much of a problem at times, you will just think you are going faster than you actually are!
Often though, the biggest problem going with smaller rims is the clearance of the brake callipers. On some cars fitted with upgraded brakes, you might be unable to fit certain wheels. Alloys with a dish or large lip can be worst, as the spokes tend to go further inwards. Spokes can catch on the calliper, making it impossible to spin the wheel. We wouldn’t recommend fitting smaller brakes obviously, why would you? For safety reasons, it is better to upgrade your brakes than downgrade them!
Fitment
Frustratingly there is no universal fitment for wheels and there are several technical factors that have to be considered when selecting new wheels for your vehicle. However, the good news is that we’ve got you covered. The Wheel Guys’ wheel selector has our expertise built-in. Simply enter your vehicle’s details and we’ll do the rest for you. No need to find the manual; no complicated VIN lookups. Our website does all the thinking, so you don’t have to. Want to understand fitment for yourself? Read on. There are 50+ fitment variations to get your head around. There are a few basic dimensions that affect the fit, the appearance and what tyres you’ll need.
PCD
PCD stands for 'pitch circle diameter' and is basically the measurement between the bolt holes. It is vital that the alloys have the same PCD as the vehicle's wheel hub.
Wheel Diameter
Wheel Diameter is the measurement across the face of the wheel, not including the wheel lips (the part of the wheel that helps keep the tyre in place)
Wheel Width
Wheel Width is the measurement from the inside of the wheel lip, across the wheel to the other lip.
Bolt Pattern Styles & Dimensions
There are four common bolt pattern styles:
4, 5, 6 & 8 lug and each can be found with several different bolt circle dimensions.
5 lug wheels are measured from the back of 1 hole, to the centre of the opposite 2 holes.
4 x 100
The number 4 refers to the number of holes in the wheel. The number 100 refers to the diameter of the circle of boltholes measured in millimetres.
Wheel Offset
Wheel Offset is the dimension from the rear of the mounting face to the centre line of the wheel.
Wheel Back Spacing
Wheel Back Spacing is the measurement from the rear of the mounting face to the back side wheel lip
Wheel Offset
Both the wheel offset and the wheel backspacing affect your vehicle’s suspension and brake clearance. There are 3 different types of wheel offset:
- Positive
- Zero
- Negative offset.
Remember that the offset is measured from the inside of the wheel’s mounting face to the true centreline of the wheel.
A positive offset wheels hub mounting surface will be shallow, closer to the street side.
A negative offset wheel will be deeper, or have a mounting face that’s closer to the back side of the wheel, than the front side.
Construction Material
Alloy wheels are typically made from a combination of aluminium and other metals. The choice of materials affects the wheel's strength, weight, and durability. Cast alloy wheels are economical and popular, while forged alloy wheels are known for their superior strength and lighter weight. Consider your driving needs and budget when choosing between cast and forged alloy wheels.
Alloy wheels are produced using different manufacturing methods, each with its unique set of strengths and weaknesses. The three main ways alloy wheels are produced are casting, forging, and flow forming.
Casting
Casting is the most common and cost-effective method of manufacturing alloy wheels. It involves pouring molten aluminium into a mould, allowing it to cool and solidify into the desired wheel shape.
Strengths:
- Cost-Effective: Casting is generally more affordable compared to other methods, making it a popular choice for mass production.
- Design Flexibility: Casting allows for intricate and complex designs, providing a wide range of styling options for consumers.
- Availability: Cast alloy wheels are widely available and come in various sizes and designs to fit different vehicles.
Weaknesses:
- Weight: Cast alloy wheels tend to be heavier than wheels produced using other methods. This additional weight can impact fuel efficiency and overall vehicle performance.
- Strength: While cast wheels are durable, they may not be as strong as forged wheels, making them more susceptible to bending or cracking under extreme driving conditions.
Forging
Forging involves shaping the wheel by applying pressure to heated aluminium billets. This process results in a stronger and lighter wheel compared to casting.
Strengths:
- Strength and Durability: Forged wheels are renowned for their superior strength and durability. They are less prone to cracking or bending, making them ideal for high-performance vehicles.
- Lightweight: Forged wheels are lighter than their cast counterparts, contributing to improved handling and performance.
- Heat Resistance: Forged wheels exhibit better heat dissipation properties, reducing the risk of brake fade during intense driving.
Weaknesses:
- Cost: Forged wheels are more expensive to produce than cast wheels, making them a premium option. The higher cost can be a limiting factor for budget-conscious consumers.
Flow Forming (Rotary Forging)
Flow forming involves the application of heat and pressure to a cast wheel, altering its molecular structure and improving its strength. The wheel is then stretched and compressed to achieve the desired shape.
Strengths:
- Balanced Performance: Flow-formed wheels strike a balance between the affordability of cast wheels and the performance benefits of forged wheels.
- Weight Reduction: Flow-formed wheels are lighter than traditional cast wheels, contributing to improved fuel efficiency and handling.
- Increased Strength: While not as strong as forged wheels, flow-formed wheels offer increased strength compared to traditional casting, providing enhanced durability.
Weaknesses
- Limited Design Options: Compared to casting, the design options for flow-formed wheels may be somewhat limited. However, advancements in technology are expanding design possibilities.
Design and Style
Alloy wheels come in various designs and styles, allowing you to personalize the appearance of your vehicle. From classic spoke patterns to intricate designs, the options are diverse. Consider the overall aesthetic of your vehicle and choose a design that complements its style. Additionally, think about the ease of maintenance, as certain designs may be more challenging to clean than others.
Classic Spoke Wheels
One of the most timeless and iconic alloy wheel styles is the classic spoke design. These wheels typically feature a set of thin, elongated spokes radiating from the wheel's centre hub to the outer rim. The number of spokes can vary, with common configurations including 5, 7, or even 10 spokes. Classic spoke wheels evoke a sense of elegance and sophistication, making them a popular choice for luxury and sports cars.
Mesh Wheels
Mesh wheels are characterized by a complex pattern of interconnected spokes, forming a mesh-like design. This style often gives the wheels a more intricate and modern appearance. Mesh wheels are known for their lightweight construction and enhanced airflow to the brakes, making them a functional choice for high-performance vehicles. The design variations within the mesh category are vast, ranging from simple and symmetrical to complex and asymmetrical patterns.
Multi-Spoke Wheels
Multi-spoke wheels feature a higher number of spokes than classic designs, often ranging from 7 to 15 or more. The increased number of spokes provides a unique visual appeal, and the style is commonly associated with both sporty and luxury vehicles. The design possibilities are endless, allowing for variations in spoke length, curvature, and spacing. Multi-spoke wheels strike a balance between classic and modern aesthetics.
Split-Spoke Wheels
Split-spoke wheels are characterized by spokes that split into two branches as they approach the outer rim. This design creates a dynamic and visually interesting look, providing a modern and sporty appearance. Split-spoke wheels are often favoured by enthusiasts looking to add a touch of aggression to their vehicle's aesthetic.
Deep Dish Wheels
Deep dish wheels are known for their distinctive deep and concave centre, creating a bowl-like appearance. This style is particularly popular in the aftermarket scene and is associated with a bold and aggressive stance. Deep dish wheels can be found in various spoke configurations, including classic, mesh, and multi-spoke designs.
Finish Options
Alloy wheels are available in a range of finishes, including polished, painted, machined, and chrome. The finish not only adds to the visual appeal but also affects the wheel's resistance to corrosion and ease of maintenance. While polished wheels may offer a high-gloss shine, painted finishes are often more resilient against harsh weather conditions.
Polished Finish
- Polished wheels have a glossy and reflective surface, resembling chrome but without the chrome's yellowish tint.
- Requires regular cleaning to maintain the shine, as it is susceptible to brake dust and environmental contaminants.
- Often found on luxury and high-end vehicles.
Chrome Finish
- Chrome wheels have a mirror-like, highly reflective surface, providing a shiny and eye-catching appearance.
- Prone to scratches and pitting, requiring diligent cleaning to prevent corrosion.
- Commonly used on classic cars and vehicles where a flashy look is desired.
Painted Finish
- Painted wheels come in a variety of colours and finishes, ranging from matte to glossy, allowing for customization to match the vehicle's colour scheme.
- Easy to maintain, though susceptible to chipping and scratching over time.
- Widely used on a broad range of vehicles for its versatility.
Matte Finish
- Matte wheels have a non-reflective, flat finish, providing a modern and understated look.
- Less prone to showing brake dust and scratches, making maintenance easier compared to glossy finishes.
- Often seen on sports cars and vehicles aiming for a contemporary, stealthy appearance.
Satin Finish
- Satin finishes have a subtle sheen, falling between matte and glossy, offering a refined look without being too flashy.
- Strikes a balance between matte and glossy finishes, making it relatively easy to maintain.
- Used on a variety of vehicles, providing a touch of elegance without being overly bold.
Diamond Cut Finish
- Diamond-cut wheels have a shiny, machined face with fine lines or patterns, creating a distinctive look.
- Requires regular cleaning and careful maintenance to preserve the machined surface.
- Often found on high-end and performance vehicles for a sophisticated appearance.
Anodized Finish
- Anodized wheels have a protective oxide layer that can be dyed to achieve various colours, offering a unique and durable finish.
- Resistant to corrosion and fading, requiring minimal maintenance.
- Common on both standard and customized vehicles for its durability and colour options.
Black or Gunmetal Finish
- Black or gunmetal wheels provide a sleek and modern appearance, often associated with a sporty or aggressive look.
- Shows less brake dust and is relatively easy to clean, making it a practical choice.
- Widely used on a variety of vehicles, especially those aiming for a bold, contemporary style.
In choosing an alloy wheel finish, personal preference, vehicle style, and maintenance considerations all play a role. Ultimately, the right finish can enhance the overall look of a vehicle and contribute to its individual character.
Quality Standards
The alloy wheel market adheres to several quality standards to ensure that products meet specific criteria for performance, safety, and durability. These standards are set by industry organizations and regulatory bodies to maintain consistency and quality across manufacturers. Here are some of the key quality standards in the alloy wheel market:
JWL (Japan Light Alloy Wheel Standard)
Originating in Japan, the JWL standard is widely recognized and adopted globally. It specifies technical requirements for the design, construction, and testing of alloy wheels. JWL standards include guidelines for load capacity, impact resistance, and dimensional characteristics to ensure safety and performance. However, the JWL is self-certified by the manufacturer and is open to being falsified.
VIA (Japanese Vehicle Inspection Association)
Unlike the JWL, the VIA test is performed by the VIA governing body which requires the wheel to be sent to their official testing facility. VIA test results can't be falsified!
TUV (Technischer Überwachungsverein)
Originating in Germany, the TÜV certification is a requirement in some European countries. It is a mark of approval that signifies a product meets certain safety and quality standards. TUV certification ensures that alloy wheels have undergone rigorous testing for structural integrity, fatigue resistance, and material quality. Passing TüV approvals can be expensive and time-consuming, so this tends to only be something that is undertaken by the big players in the industry.
ISO Standards (International Organization for Standardization)
ISO 9001 and ISO/TS 16949 are quality management standards that some alloy wheel manufacturers adhere to. ISO 9001 focuses on general quality management, while ISO/TS 16949 specifically addresses quality in the automotive supply chain, ensuring consistency and adherence to automotive industry requirements.
EN Standards (European Norms)
EN standards are widely used in Europe and cover various aspects of alloy wheel manufacturing, including material specifications, dimensions, and testing procedures. EN 12467 is an example of a standard that specifies requirements for alloy wheel safety.
OEM (Original Equipment Manufacturer) Approvals
Alloy wheel manufacturers often seek approvals from vehicle OEMs. Meeting the specifications set by vehicle manufacturers ensures that the alloy wheels are compatible with specific vehicles and meet the performance requirements outlined by the original equipment specifications.
Consumers looking to purchase alloy wheels can consider these quality standards and certifications as indicators of a product's reliability and adherence to industry-accepted benchmarks. Additionally, reputable manufacturers often conduct in-house testing and quality control measures to maintain high standards for their products.