Parts Overview

Before beginning, familiarise yourself with the four main components of the centre cap assembly.

The complete BBS E38 E39 style 5 center cap assembly consists of:

• Wheel threaded adapter (alu)
• Waffle plate d = 172 mm (alu)
• Threaded 58 mm hexagon – RS compatible (alu)
• Emblem holder (plastic)

The adapter is secured to the wheel with three Allen screws.

The only standard tool required is a suitable Allen key. An optional Mod-ing wheel hex key wrench is also available for easier tightening and removal of the outer hexagon.

Step 1 – Position the Wheel Adapter

Begin with the adapter, which is the part mounted directly to the wheel.

Place the adapter into the centre opening and locate the three mounting screws. Do not fully tighten them yet, as the waffle plate must first be correctly positioned.

The adapter includes a small alignment tab. Position this tab so that it points towards the corresponding alignment line on the wheel.

Correct alignment is important because it determines the final orientation of the waffle plate.

Step 2 – Install the Waffle Plate

Place the waffle plate over the loosely fitted adapter.

The waffle plate includes a locating notch that fits directly over the alignment tab on the adapter. Rotate the plate until the notch and tab line up correctly.

Once aligned, the waffle plate should sit evenly against the wheel without being forced into position.

Before tightening anything, check that:

• The adapter tab points towards the alignment line on the wheel.
• The waffle plate notch sits over the adapter tab.
• The plate is centred inside the wheel.
• The outer edge sits evenly all the way around.

Step 3 – Secure the Adapter

With the adapter and waffle plate correctly aligned, tighten the three Allen screws.

Tighten them gradually and evenly rather than fully tightening one screw at a time. This helps the adapter pull into position squarely and prevents the centre cap from sitting at an angle.

Once properly secured, the adapter should remain fixed inside the wheel and should not fall out when the waffle plate is handled.

Avoid excessive tightening. The screws only need to hold the adapter securely in place.

Step 4 – Install the Hexagon

Take the threaded hexagon and carefully screw it into the centre adapter by hand.

The threads should engage smoothly. If the hexagon feels tight immediately or begins to sit at an angle, remove it and start again. Never force the part, as this may damage the threads.

Once it has been correctly started by hand, tighten the hexagon using the optional Mod-ing hex key wrench.

The wrench provides better leverage and helps tighten the cap evenly without marking the outer surface.

The hexagon only needs to be tightened until the waffle plate is held securely against the wheel.

Step 5 – Install the Centre Emblem

The hexagon is designed to accept original-style three-prong BBS emblems and other compatible emblems using the same mounting system.

Align the three retaining prongs with the openings in the hexagon and press the emblem evenly into place.

Avoid pressing heavily on one side only, as this may bend the emblem prongs.

A blank emblem holder is also included with the assembly. This can be used with a flat adhesive emblem of your choice, including a OEM 70 mm BMW round emblem , BBS 3D emblem or another custom badge.

Clean the emblem holder before applying a sticker emblem to ensure proper adhesion.

Final Inspection

Before driving, inspect the complete centre cap assembly.

Confirm that:

• All three adapter screws are secure.
• The adapter does not move inside the wheel.
• The waffle plate is correctly aligned.
• The threaded hexagon is fully engaged.
• The emblem is seated securely.
• The centre cap sits evenly without rattling.

It is good practice to check the centre caps again after the first drive, particularly if the wheels have recently been painted or powder coated.

Installation Tips

When mounting BBS style 5 16″ 5×120 custom aluminum wheel center cap always begin threading the hexagon by hand. Using the wrench too early can hide incorrect thread engagement and increase the chance of cross-threading.

If the wheel has recently been refinished, inspect the centre opening and screw locations before installation. Excess paint or powder coating can prevent the adapter from sitting flush.

Do not use impact tools when installing the screws or outer hexagon. Hand tools provide enough force and make it easier to feel whether the components are seated correctly.

The Mod-ing RS-look centre cap system is a visual conversion for original BMW Style 5 wheels. It provides the appearance of a classic BBS RS-style centre while retaining the original wheel mounting arrangement and allowing straightforward access to the wheel bolts.

Video Tutorial

Prefer watching the complete process before starting? The video tutorial shows how to position the adapter, align the waffle plate, tighten the mounting screws, install the hexagon and fit the centre emblem.

The written guide below follows the same steps, making it easy to keep each stage open while working on the wheel.