You can recognize concave rims at first glance: the spokes do not run flat to the center of the wheel, but rather curve noticeably inwards from the outer rim edge towards the hub. The wheel appears like a bowl, deep, sculptural, and much more three-dimensional than a classic, flat design. This guide explains how this look is technically achieved, why the same rim doesn't look equally concave on every car, the role of offset, rim width, and load capacity, and what you need to consider when buying to ensure that a head-turner doesn't turn into a problem when it comes to approval.
Note: "Concave" and "Deep Concave" are manufacturer design designations, not standardized measurements. How deep a rim actually appears on your vehicle depends on the specific dimension, i.e., the width, offset, and size of the respective variant. The documents for the specific rim-vehicle combination are always binding for installation and approval.
1. What concave rims are and what distinguishes them from the rest
With a flat or convex rim design, the spokes are largely flush with the outer rim edge or even curve slightly outwards. With a concave design, it's the opposite: the spoke's connection point to the hub sits significantly deeper in the wheel than the rim flange. The greater this offset, the deeper the "bowl" and the stronger the concave effect.
Manufacturers often categorize this in stages such as "Concave," "Deep Concave," or "Super Deep Concave." However, such designations cannot be compared between brands, as there is no standard for how many millimeters of spoke depth make a rim "deep." What matters is looking at the specific variant: the same series can appear almost flat in 8x19 with a high offset and extremely deep in 10x22 with a low offset.
The look became popular in the tuning scene of the 2010s, when wide wheels with deep spokes became a hallmark first in motorsports and then in the street scene. Today, concave has long since arrived in series accessories: many manufacturers design their sporty series from the outset with inwardly drawn spokes, and even in the off-road sector, the strong bowl is standard repertoire, less for stylistic reasons than simply as a result of the wide dimensions with low offset.
2. How the curvature is technically created: Width and offset
The bowl depth is not magic, but rather geometry derived from two measurements. Firstly, the jaw width, i.e., the rim width: the wider the rim, the more space there is between the rim flange and the hub mounting surface, which the design can translate into depth. Secondly, the offset: it describes the distance between the wheel center and the mounting surface. A low or negative ET pushes the wheel further outwards, the outer rim bed builds deeper, and the spokes can be pulled further inwards accordingly.
Therefore, the rule of thumb is: Wide rim plus low ET results in strong concavity. And that's why the deepest designs are typically found on the rear axle, where wider wheels are mounted on vehicles with mixed tires. Our guide Rim width and tire width explains which tire width belongs to which jaw width.
A numerical example makes the magnitude tangible: If you switch from ET45 to ET25 with the same rim width, the mounting surface shifts by 20 millimeters, the wheel stands 20 millimeters further out per side, and precisely this distance is additionally available to the design as bowl depth. If you simultaneously take a rim that is one inch wider (i.e., 25.4 millimeters more jaw width), another good twelve millimeters are added on the outside, depending on the distribution. This explains why there is often only one dimension between "slightly curved" and "deep bowl" and why you should never judge concavity by a catalog photo, but always by the ET and width of the specific variant.
The flip side of the same geometry: what pulls the spokes inwards must find space on the vehicle. Outward, the bodywork with the wheel arch cover limits the leeway; inward, on many vehicles, the brake system sits exactly where a deep bowl wants to be. Large brake calipers and strongly concave designs do not automatically get along; the expert opinion and the clearance check decide.
3. Cast, flow-formed or forged: Stability of the deep spoke
A deeply drawn spoke is mechanically a longer lever, and the wheel must still bear the full axle load. Manufacturers solve this through material and manufacturing: classic casting with a correspondingly robust design, flow-forming with a compressed, thinner rim bed, or forged wheels, which offer the highest strength at low weight. We have described the differences between the three processes in detail in the guide Flow Forged vs. Cast Rims.
For you as a buyer, one value ultimately counts: the load capacity of the rim, which must match the axle load of your vehicle. A deep design in itself says nothing about stability, neither positively nor negatively; the tested values in the expert opinion are decisive. How to calculate the wheel load and where to find it is shown in the guide to Rim Load Capacity.
4. On which vehicles does Concave have a strong effect
The optics live from the ratio of wheel diameter, rim width and bodywork. Three typical cases:
Sedans and Coupés with rear-wheel drive: The classic. Wide rear wheels, often with mixed tires, give the design the space it needs. From 19 inches, the effect becomes clearly visible; in 20 to 22 inches, it dominates the side view. Mixed tires mean: narrower at the front, wider at the rear, for example 8.5 inches jaw width on the front axle and 10 inches at the rear. The rear wheels therefore appear visibly deeper than the front wheels, which many consciously want as a gradation. It is only important that both dimensions are listed in the expert opinion, because mixed tires are a separate approval item and not a free combination.
SUVs, Pick-ups and Off-road vehicles: Off-road designs often work with low offsets around ET25 down to the single-digit range, so that the wheel sits wide in the wheel arch. Precisely this geometry automatically creates a strong bowl, which is why many off-road wheels are designed concave, even if the word is not mentioned in the brochure.
Compact cars with front-wheel drive: Here, the approved offsets are usually higher, so the concave effect is inherently more subtle. This is not a defect of the rim, but rather vehicle geometry.
In terms of color, dark surfaces enhance the depth effect because shadow edges are more pronounced. Our guide to black rims explains what distinguishes matte, glossy, and gunmetal finishes.
5. Concave designs at zrshop
In our assortment, you will find the effect in both worlds. On the road side, there's the Corspeed Atmos in 9.5x21 and 9.5x22 with bolt circles from 5x108 to 5x114.3, a classically sporty design with deeply drawn spokes. On the off-road side, our house brands deliver powerful bowls through low offsets: the RID R05 in 10x22 ET5 as an extreme example, plus the DIRT-Designs D42 (9x18 ET25) and D62 (9x20 ET25) for pick-ups and off-road vehicles with a 6x114.3 bolt circle.
When comparing in the shop, it's worth looking at two specifications in each product title: the jaw width before the "x" and the ET behind it. Two wheels of the same series in 9x20 ET25 and 8.5x20 ET45 will look significantly different when mounted, even though the photo and design appear identical. And for SUVs and pick-ups, the wheel load must be noted: heavy vehicles require correspondingly high tested values, so the deep look is only available within what the expert opinion allows for your vehicle weight.
View Corspeed Rims in the Shop
If you prefer to start from the vehicle: The configurator filters the assortment to the sizes and offsets that match your model, from there you compare the designs. For a comprehensive overview by diameter, starting with the 20-inch collection is worthwhile, where concave designs are naturally most frequently represented.
6. Approval: what needs to be checked for deep designs
Legally, the same rules apply to concave rims as to any other wheel, but the critical points are more often relevant due to the typical geometry (wide, low ET):
Wheel arch clearance: If the wheel protrudes further due to the low offset, it must still be covered by the bodywork. Whether this is the case is part of the assessment of the combination.
Freedom of movement: Brake, suspension, and bodywork need clearance in every steering and compression position. Especially brake caliper clearance is the most common reason for exclusion with deep dishes.
Documents: If the rim has an ABE (General Operating Permit) whose vehicle list includes your type with all requirements, installation may be permissible without acceptance. With a parts certificate, the path leads through an alteration inspection at an officially recognized testing center. The complete process is described in the guide How to successfully register rims with TÜV, and what is behind the test number on the rim is explained in the article on the KBA number.
A word about a popular workaround: Anyone who wants to recreate the deep look on a flatter rim using spacers changes the effective offset of the wheel, with the same consequences for wheel coverage, clearance, and load capacity of the attachments. This can work, but it also requires tested documentation just like the rim itself. What needs to be considered is stated in the Wheel Spacer Guide; in our assortment, we carry suitable spacers in various thicknesses including accessories.
7. Everyday life with deep dish: curb, care, winter
The further the rim flange protrudes and the deeper the dish, the more expensive contact with the curb becomes, because the flange is usually the furthest protruding point of the wheel in concave designs. Tires with rim protection ribs (designed as a bead over the flange in the tire profile) cushion minor touches, but do not replace caution. When maneuvering, an extra look is worthwhile, when parking, keeping a distance from the edge. If scratches do occur, the same applies as to any wheel: cosmetics are one thing, structural damage to the flange must be professionally assessed.
For cleaning, the deep spoke valleys are best reached with a soft rim brush instead of a high-pressure jet from close range. Especially in the valleys, brake dust and road salt residues collect, which you should not let dry on glossy and diamond-cut surfaces. An acid-free cleaner and regular, short washes protect the surface more than rare basic cleanings with harsh chemicals.
For the winter season, two points speak for a second set of wheels with a more robust surface: salt and grit attack sensitive surfaces, and the deep valleys hold slush longer than flat designs. Many therefore use their concave wheels as summer attire and a less sensitive set in winter, which incidentally eases the question of balance weights: weights glued inside remain invisible with the summer look, while weights hammered on the outside disturb it.
FAQ about concave rims
Do I have to register concave rims?
That doesn't depend on the design, but on the documents for the specific rim-vehicle combination. With a suitable ABE without restrictions, installation may be permissible without acceptance; with a parts certificate, an alteration inspection at an officially recognized testing center is necessary.
What does Deep Concave mean?
A marketing categorization by manufacturers for particularly deeply drawn spokes. The term is not standardized; the actual depth depends on the width and offset of the respective variant.
Are concave rims less stable?
No, provided the rim is approved for your vehicle. The load capacity is checked for each variant and documented in the expert opinion; manufacturing processes such as flow-forming or forging structurally compensate for the longer spoke paths.
Why don't the same rims look equally concave on every car?
Because the dish depth depends on the dimension. A narrow variant with a high offset will appear shallower than the wide variant with a low ET, even if both belong to the same series.
Are concave rims also available for compact cars with front-wheel drive?
Yes, but the effect is inherently more subtle because the approved offsets are usually higher there. Select your vehicle in the configurator and compare the available variants: within the approval, the widest variant with the lowest ET will achieve the deepest look.