BMW E90: Alloys & More

The BMW 3 Series E90, a benchmark in the sport sedan category for decades, offers a fantastic platform for customisation. Whether you're aiming for a subtle enhancement or a dramatic transformation, understanding the right modifications can elevate your driving experience. This guide delves into the crucial aspects of upgrading your E90, focusing on alloy wheels, suspension, exhaust systems, exterior styling, performance cooling, lighting, and braking. We'll explore options that cater to various tastes, from a clean, classy look to a more aggressive, track-inspired stance.

1. The All-Important Alloy Wheels

When it comes to transforming the aesthetic of your BMW E90, alloy wheels are arguably the most impactful upgrade. While factory options can be underwhelming, a well-chosen set of aftermarket or genuine BMW alloy wheels can dramatically alter your car's presence. The E90 chassis, praised for its driving dynamics, also provides a great canvas for showcasing stylish rims. Whether you prefer a classic multi-spoke design, a modern concave look, or something more aggressive, there's an option to suit.

Choosing the Right Fitment

Selecting the correct wheel size, offset (ET), and bolt pattern is paramount for a perfect fit and optimal performance. For the E90 3 Series, common wheel sizes range from 17 inches to 19 inches, with some enthusiasts opting for 20 inches. The bolt pattern is typically 5x120, and the centre bore is 72.56mm. Offset plays a crucial role; a lower ET will push the wheel further out from the hub, while a higher ET tucks it in. For instance:

Popular Wheel Brands and Styles

• Avant Garde Wheels: Known for clean, stylish designs like the M510, offering a distinct look.
• Forgestar Wheels: Custom-made to order, offering various concave profiles (Semi, Deep, Super Deep) for a truly bespoke appearance. The F14 is a popular choice.
• VMR Wheels: A long-standing favourite for the E90 platform, with models like the V710 and V718 offering excellent aesthetics and quality.
• Sportline 8S: These wheels offer a sharp look with a subtle concave design, available in various finishes and sizes, often at a budget-friendly price point.

Remember, achieving an aggressive fitment, especially with wider or more concave wheels, might require modifications such as fender rolling or adjustable suspension components.

2. Enhancing the Sound and Look: Exhaust Systems

The exhaust system on your E90 is more than just a functional component; it's a key element in defining your car's character. Upgrading your exhaust can significantly alter the engine's sound profile and the rear-end aesthetics. Whether you own a 328i or a more powerful 335i, there are numerous options to consider.

Exhaust Options for E90

• Remus Exhaust: Offers a throatier, distinctly European tone, often featuring stylish carbon fibre tips, particularly popular for the 335i.
• HKS Cat-Back Exhaust: Known for its tuner-esque sound and performance gains, it's a well-regarded option for the 335i.
• BMW Performance Exhaust: A favoured choice for both 328i and 335i models, providing a refined yet sporty sound. The single-exit setup for the 328i is particularly neat.
• Cobb Tuning Cat-Back Exhaust: Designed for the N54/N55 engines, it offers a unique sound and complements other Cobb tuning parts.

When choosing an exhaust, consider not only the sound clips but also the long-term impact of the volume and tone. It's a personal preference, so listening to various systems is crucial.

3. Lowering the Stance: Suspension Upgrades

A lowered vehicle inherently looks more aggressive and purposeful. Beyond aesthetics, upgrading your suspension offers tangible performance benefits, including sharper handling, a lower centre of gravity, and often an improved ride quality when done correctly. For the E90, you have three primary avenues:

Suspension Choices

• Lowering Springs and Shocks: A straightforward way to lower the car and improve handling. Popular choices include Eibach Pro-Kit and H&R Sport Springs, often paired with performance shocks like Koni or Bilstein.
• Coilovers: These offer adjustable ride height and damping, allowing for fine-tuning of your car's stance and handling characteristics. Brands like KW Suspensions, BC Racing, and ST Suspensions are highly regarded. For a more budget-conscious option, Solo-Werks provides a solid entry point.
• Air Suspension: For ultimate adjustability and the ability to achieve extreme lows on demand, air suspension systems like Airrex are available, though at a significantly higher cost.

It's worth noting that as E90s age, original shocks will likely need replacement. Opting for coilovers during this process offers a more comprehensive upgrade.

4. Crafting Your E90's Exterior

Personalising the exterior of your E90 allows you to truly make it your own. From subtle enhancements to more pronounced styling cues, there are many options available for various bumper configurations.

Front-End Styling

• Front Lips and Splitters: These add a touch of aggression to the front bumper. Options range from HM Style lips for non-M-Sport models to M-Sport style splitters and lips for those with the M-Sport package.
• M-Sport Style Bumpers: For E90s without the factory M-Sport package, an aftermarket M-Sport style bumper can dramatically change the front-end appearance.
• M3 Style Bumpers: Achieving the E90 M3 look is possible with aftermarket M3 style bumpers, though fitting an actual E90 M3 bumper requires significant modifications due to its wider track.

Side Skirts and Rear Styling

• Side Skirts: M3 Style side skirts are a prevalent option, offering a sleek look for both coupe and sedan variants.
• Rear Bumpers: The M-Sport Style rear bumper is a popular choice. If opting for an M3 style rear bumper, be mindful of exhaust tip placement, as standard E90 exhausts may not align correctly.
• Diffusers: A Performance Style or 3D Style carbon fibre rear diffuser can further enhance the rear aesthetics, often complementing the M-Sport bumper.
• Trunk Spoilers and Decks: From subtle Performance Style carbon fibre spoilers to more pronounced M3 Style trunk spoilers or even a CSL Style trunk lid, these can refine the rear end.

5. Keeping Cool: Performance Oil Coolers

The turbocharged N54 and N55 engines, and even naturally aspirated variants, can run hot, especially under spirited driving conditions. Insufficient cooling can lead to overheating, potentially triggering 'Limp Mode' and reducing engine longevity. Many E90 models, particularly early N54/N55 variants, either lacked an oil cooler or had an undersized one.

Why an Oil Cooler is Crucial

An upgraded oil cooler is a vital modification for any E90 owner who enjoys spirited driving or wants to protect their engine. By maintaining lower oil temperatures, it ensures proper lubrication, reduces wear, and prevents potential damage. This is especially important for turbocharged engines where heat management is critical.

6. Illuminating Your E90

Lighting upgrades not only improve visibility but also significantly enhance your E90's modern appeal. From headlights to tail lights, there are several ways to update the illumination.

Lighting Enhancements

• HID Headlights: If your E90 has halogen headlights, upgrading to an HID kit can provide a brighter, more focused beam.
• LED Angel Eyes: Replacing the stock yellow "halos" with bright white LED Angel Eyes from brands like LUX transforms the front-end signature.
• LED Sidemarkers: Smoked or clear LED sidemarkers offer a cleaner look and improved brightness over stock units.
• LCI LED Tail Lights: These OEM BMW LED tail lights offer a modern look and hassle-free installation, avoiding common error codes associated with some aftermarket LEDs. Other aftermarket LED tail light styles are also available in various finishes.
• Interior and Plate LEDs: Upgrading interior courtesy lamps and license plate lamps with LEDs provides a crisp, uniform illumination throughout the vehicle.

7. Stopping Power: Brake Upgrades

While often overlooked until they become an issue, brakes are a critical safety and performance component. The E90's braking system can be significantly improved without resorting to expensive big brake kits.

Improving Braking Performance

A StopTech Stage 2 brake package is an excellent example of a comprehensive yet affordable upgrade. This typically includes:

• Larger diameter brake rotors
• Performance brake pads
• Stainless steel braided brake lines
• High-performance brake fluid

This combination results in firmer pedal feel, improved responsiveness, and greater resistance to brake fade, enhancing both daily driving confidence and track performance. Additionally, larger wheels can better showcase upgraded brake components.

Frequently Asked Questions

What is the standard wheel size for a BMW E90?

Standard wheel sizes for the BMW E90 typically range from 16 to 18 inches, depending on the specific model and trim level. However, 17 and 18-inch wheels are the most common for a good balance of comfort and performance.

Can I fit larger wheels on my E90?

Yes, it is common to fit larger wheels, such as 19-inch or even 20-inch wheels, on the E90. However, careful consideration of the wheel's width, offset (ET), and the corresponding tire size is crucial to avoid rubbing against the fenders or suspension components. Consult with a specialist or use a reliable wheel fitment guide.

What does the ET number mean on a wheel?

The ET number, also known as offset, indicates how far the wheel's mounting surface is from the centerline of the wheel. A positive ET means the mounting surface is towards the outside of the wheel, while a negative ET means it's towards the inside. For the E90, common offsets are in the ET30 to ET47 range, but this can vary based on wheel width and desired fitment.

Are coilovers better than lowering springs?

Coilovers offer more adjustability in terms of ride height and damping, allowing for a more tailored setup for both performance and aesthetics. Lowering springs are a simpler, often more affordable option, but they typically do not offer damping adjustability and can sometimes lead to a harsher ride if not paired with appropriate shocks.

What is 'Limp Mode' on a BMW E90?

'Limp Mode' (or Limp Home Mode) is a safety feature that reduces engine power and performance when the car's computer detects a serious issue, often related to engine temperature, turbocharger performance, or other critical systems. Overheating due to inadequate cooling can trigger this mode.

How do I know if my E90 needs an oil cooler?

If you frequently engage in spirited driving, track days, or notice your oil temperature rising significantly under load (often above 230°F or 110°C), your E90, particularly with the N54 or N55 engine, would greatly benefit from an upgraded oil cooler.

Upgrading your BMW E90 is a rewarding process. By carefully selecting the right alloy wheels, suspension, exhaust, and other enhancements, you can significantly improve both the look and performance of your 'Ultimate Driving Machine'. For expert advice and assistance with any of these modifications, reaching out to specialists is always recommended.