A two-piece automotive modular wheel, sometimes referred to as a "two-piece wheel," is a type of wheel used in vehicles, particularly in the automotive and racing industry. It consists of two main components:

Center Section | This is the inner part of the wheel, often made from materials such as aluminum or steel. It typically includes the hub mounting surface, which attaches to the vehicle's axle, and the portion that connects to the tire.

Outer Rim Section | The outer rim, or outer barrel, is the second part of the two-piece wheel. It is attached to the center section and forms the outer edge of the wheel. The outer rim can be designed in various styles and sizes and is often replaceable, allowing for customization.

A three-piece automotive modular wheel, often referred to as a "three-piece wheel," is a type of wheel commonly used in custom and high-performance automotive applications. Unlike traditional one-piece wheels, which are manufactured as a single unit, three-piece wheels are constructed from three separate components: the center disk, the outer barrel, and the inner barrel.

Here's a brief overview of these components:

Center | This is the central portion of the wheel, and it contains the bolt pattern and hub mounting surface. The center disk is typically the most customizable part of a three-piece wheel, allowing for various finishes, designs, and even branding options. It's the part of the wheel that attaches to the vehicle hub.

Outer Lip | The outer barrel is the part of the wheel that forms the outermost edge and lip of the wheel. It can also be customized in terms of size and design. Different outer barrels can change the width and appearance of the wheel.

Inner Barrel | The inner barrel is the piece that connects the center disk and the outer barrel. It provides structural support and is usually designed to meet specific requirements, such as brake clearance and offset. The inner barrel can also vary in width to accommodate different tire sizes and applications.

Three-piece wheels offer several advantages, including the ability to create custom looks, achieve specific fitments, and choose from various finishes. They are popular in the aftermarket automotive industry, especially for car enthusiasts who want to personalize their vehicles. These wheels are often used on sports cars, luxury vehicles, and in motorsport applications.

Converting a 2-piece split modular wheel into a 3-piece split modular wheel involves disassembling the existing 2PC wheel and creating a new configuration with three separate components utilising the centre/face.

With using a lip and barrel as separate components now and using the centre from the 2pc, a 3pc can be created. Simple as that.

Sometimes this may require machining but the conversions are more popular than ever! BBS's are used by many car manufacturers across the world on their cars from factory using 2pc wheels which can be converted. Examples such as BBS RC's, RT's, Audi Speedlines just to name a few..