D-Shaped or Round Rim: Which Steering Shape Fits You

What is a D-shaped rim

A D-shaped rim, also called a flat-bottom rim, has a straight edge at the bottom instead of a full curve. The shape resembles the letter D when viewed from the front. This design is common on GT-style and formula-style racing wheels, as covered in the best force feedback racing wheels guide.

The flat bottom creates extra clearance between the rim and your legs, which can make getting in and out of a cockpit easier and allow you to sit closer to the wheel. It also encourages a fixed hand position at 9 and 3 o'clock, the standard grip for most circuit racing.

Many racing wheel listings describe a rim as "D-shaped" or "flat-bottom" in the title or bullet points. When you see those words, the wheel is designed for a driving style that does not require full rotation of the rim.

What is a round rim

A round rim is a full circle with no flat sections. It is the traditional shape found in road cars and older racing wheels. Round rims are still used in many sim racing wheels, especially those aimed at drifting, rally, and vintage car simulations. For more on drifting-specific features, see the drifting wheel features article.

The full circle allows you to slide your hands around the rim during hand-over-hand steering, which is essential for drifting and for making sharp turns in rally stages. You can grip at 10 and 2, 9 and 3, or anywhere in between, depending on the corner.

Round rims are also common on entry-level racing wheels and on wheels designed for truck or farm simulator games, where a large steering angle is part of the experience.

Grip positions and driving style

The shape of the rim directly affects where you place your hands and how you turn the wheel. A D-shaped rim naturally guides your hands to the sides, making it easy to keep a consistent grip during long races. Paddle shifters are within easy reach from this position.

A round rim gives you the freedom to change hand positions quickly. For drifting, you often need to catch the wheel as it spins back, which requires a full circle. For rally driving, you may need to turn the wheel more than 180 degrees, and a round rim lets you do that without losing grip. The round vs D-rim for drifting article explains this in more detail.

If you plan to switch between different driving styles, a round rim is more versatile because it can be used for both fixed-hand and hand-over-hand techniques. A D-shaped rim is less comfortable for hand-over-hand steering because the flat edge interrupts the circle.

Compatibility with wheel bases

Most wheel bases on the market accept both D-shaped and round rims, as long as the rim uses the same quick release or bolt pattern as the base. Many makers sell rims separately, so you can change the shape without replacing the base. The quick release system article covers how these attachments work.

When you buy a complete wheel and base bundle, the rim shape is already chosen. If you want to switch shapes later, check whether the maker offers a separate rim that fits your base. Quick release systems make this swap fast, as shown on the Fanatec and Logitech G product pages.

For a first wheel, the shape matters less than the force feedback and platform compatibility. You can always add a different rim later. The guides on this site list complete bundles and separate rims by their stated details.

Which shape for which sim

For Gran Turismo, Assetto Corsa Competizione, and other GT or circuit racing sims, a D-shaped rim is a natural fit. The flat bottom matches the feel of a real GT car and keeps your hands in the right position for paddle shifting. The best racing wheel guide includes options for GT-style wheels.

For drifting sims like Assetto Corsa (with drift mods) or CarX Drift Racing, a round rim is the better choice. The full circle lets you perform the steering corrections and countersteering that drifting requires.

For rally sims such as DiRT Rally 2.0 or WRC, a round rim is also preferred because of the large steering angles and the need to catch the wheel quickly. Some rally wheels have a slightly smaller diameter for faster rotation.

For formula or open-wheel sims, a D-shaped or even a rectangular formula-style rim is standard. These rims often have a smaller diameter and a flat top as well, but the key feature is the flat bottom for leg clearance.

Other considerations

Rim diameter also affects your choice. A larger round rim (around 330 mm) gives more leverage and is common on drift wheels. A smaller D-shaped rim (around 300 mm) feels more responsive and is typical for GT and formula wheels. The wheel diameter size guide explains how diameter affects handling.

If you share your wheel with other drivers, a round rim is usually more accommodating because it fits different hand sizes and driving styles. A D-shaped rim may feel awkward to someone used to hand-over-hand steering.

The material of the rim (leather, suede, Alcantara) is independent of the shape. Both D-shaped and round rims come in various materials. The choice of material affects grip with gloves, but the shape determines the steering technique. See the wheel rim material comparison for more details.

What to pick for your situation

Questions

Can I use a D-shaped rim for drifting?

You can, but it is not ideal. The flat bottom makes hand-over-hand steering less comfortable, and you may find it harder to catch the wheel during spins. A round rim is the standard choice for drifting. The round vs D-rim for drifting article goes into more detail.

Is a round rim better for beginners?

Many beginners start with a round rim because it is more forgiving and works for a wider range of games. If you are not sure which driving style you will prefer, a round rim gives you the most flexibility.

Do all racing wheel bundles include a rim?

Most bundles include a rim attached to the base. Some high-end systems sell the base and rim separately. Check the listing title: if it says "wheel and pedals" it usually includes a rim. If it says "wheel base" only, you need to buy a rim separately.

Can I swap a D-shaped rim for a round rim on the same base?

Yes, if the base uses a standard quick release or bolt pattern and the maker offers a compatible rim. Many makers like Fanatec, Thrustmaster, and Logitech G sell separate rims that fit their bases. The quick release system article explains the attachment standards.

Does rim shape affect force feedback feel?

The shape itself does not change the force feedback output from the base. However, a larger round rim can feel slightly less responsive because the force is spread over a larger diameter. The difference is small and depends on the torque of the base.

Are there rims that are neither D-shaped nor round?

Yes, some rims have a flat top and bottom (sometimes called a "square" or "rectangular" rim), common on formula wheels. Others have a slight flat bottom but are mostly round. The two main categories are D-shaped and round, with formula-style as a variation of D-shaped.

What about oval or asymmetrical rims?

Oval rims are rare in sim racing and are usually found in real oval racing. Asymmetrical rims are not standard. For sim racing, stick with D-shaped or round unless you have a specific need.