2018 Ford Mustang (S550) | Staggered 21" 2-Piece Forged · Matte Silver Center + Polished Lip

Engineering Notes

Concavity is the defining geometry here. Each spoke begins around a raised center section and sweeps into the wheel face before meeting the outer rim, which means the transition has to remain clean over a relatively large 21-inch surface. With only five broad spokes, machining quality is unusually exposed: curvature, spoke thickness and the transition into the rim are all easy to read from an oblique angle.

Two-piece construction gives that concave profile more freedom than a visually flat one-piece design. Front fitment uses 21×10 ET30, while the rear grows to 21×11.5 ET50. Those figures do not simply create “more dish” at the back; they establish two different wheel envelopes around the same five-spoke language, allowing the rear to gain width without making the front look undersized.

Material contrast follows the construction rather than fighting it. Matte silver belongs to the forged center, where softer reflections keep the spoke shape easy to read. Polish is reserved for the separate rim section, so brightness naturally follows the wheel depth. Exposed assembly hardware sits between those surfaces without becoming the dominant visual feature.

Hub-centric dimensions are recorded at 5×114.3 with a 70.5 mm center bore and 60° taper seat. Those values belong to this specific S550 project and should stay connected to the actual wheel drawing rather than being generalized across every Mustang fitment.

From Design to Delivery

Assembly integrity deserves particular attention on this wheel because the polished rim and forged center only achieve their intended relationship after final bolting, sealing and dimensional verification. Any inconsistency at that stage can affect both fitment and how evenly the wheel presents its concave profile.

• CMM dimensional inspection on PCD, bore & offset
• Torque-spec assembly hardware, sealed & pressure-tested
• Dynamic balancing on every wheel

Result

Depth rather than decoration defines the finished wheel. Viewed square-on, the five-spoke center feels restrained and almost classical. Move toward the rear three-quarter angle and the polished rim begins to dominate, revealing how much more volume the 21×11.5 rear carries.

That changing character is what makes the design work on the S550. It is not trying to mimic a track wheel or overwhelm the car with spoke detail; proportion, concavity and exposed forged metal do the work.

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Front Concavity and Rear Volume Serve Different Roles

21×10 ET30 Front keeps enough depth in the center to create a genuine concave profile without making the steering end visually heavy.

21×11.5 ET50 Rear adds 1.5 inches of width, giving the back considerably more physical rim volume while retaining the same diameter.

Rather than forcing both axles into the same face position, this approach allows each wheel to work with its own available space.

Why Five Spokes Are Enough

Dense mesh designs often rely on complexity for visual impact. This wheel takes the opposite approach.

Large spoke surfaces make the quality of the forging, CNC profile and concavity immediately visible. Negative space between the spokes also leaves the polished rim easier to see, which is important when the outer section is one of the wheel's main design features.

Genuine 2-Piece Character

Visible hardware and a physically separate rim section give the wheel a construction language that cannot be reproduced convincingly with decorative bolts on a monoblock.

Serviceability is another benefit already reflected in the existing page: separate sections make future refinishing more practical than treating the complete wheel as one finished surface.

For another S550 build, Xingtu can develop the concavity, width and rim depth around the actual vehicle rather than simply reproducing ET30 / ET50.

1. What sizes are used on this Mustang S550?

Front wheels measure 21×10, while the rear wheels are 21×11.5.

2. Why does the rear use ET50 instead of copying the front ET30?

Rear width changes substantially, so the wheel position also needs its own geometry. Offset and width have to be considered together rather than independently.

3. What creates the deep-concave appearance?

Spoke curvature, center position, wheel width and the independent rim section work together to create the depth; it is not simply a decorative lip.

4. Is the polished outer section separate from the matte silver center?

Yes. Current specifications identify genuine 2-piece forged construction with a matte silver center and polished lip.

5. What hub dimensions are used?

This project records 5×114.3 PCD and a 70.5 mm center bore.

6. Can the polished lip depth be changed?

Potential rim depth depends on wheel width, offset, brake clearance and the selected face profile, so another Mustang setup needs to be developed around its own dimensions.