Quick answer: Cast wheels are made by pouring molten aluminium into a mould. They're the most affordable to make and offer the widest range of styles. Flow-formed wheels start as a casting, but the barrel is then spun and rolled under pressure, which makes it denser and allows a lighter build. Forged wheels are machined from a solid block of compressed aluminium. In our range they're made to order from 6061-T6. Every SW wheel, cast or flow-formed, is certified JWL, VIA and AS1638.
Cast wheels
Casting is the most common way to make an alloy wheel. Molten aluminium alloy fills a mould shaped like the finished wheel, then the wheel is heat-treated, machined and finished. Because the shape comes from a mould, casting suits detailed designs such as deep dishes, mesh faces and multi-spoke patterns. It also keeps the price down.
A cast wheel has to be thick enough everywhere to meet its strength targets, so for the same size a cast wheel is usually heavier than a flow-formed or forged one. For most street cars that's a fair trade for the price and the style.
SW cast wheels: SW04, SW05, SW06, SW08, SW10, SW12, SW13, SW17, SW18 and SW23.
Flow-formed wheels
Flow-forming (also called rotary forging or flow-forging) begins with a cast wheel that has a short, thick barrel. The wheel is spun at speed while rollers press the barrel outward and stretch it to its full width, usually with heat applied. This compresses and stretches the aluminium in the barrel, making it denser and stronger than a straight casting. That means the barrel can be thinner and lighter for the same strength. The face and spokes stay cast.
The result sits between cast and forged: lighter than an equivalent cast wheel, for well under the cost of forged. That's why flow-forming is popular for performance street cars and track-day cars.
SW flow-formed wheels: SW01, SW02, SW03, SW07, SW09, SW14, SW15, SW16, SW19, SW20 and SW22. The 4x4 SW11 and SW21 are flow-formed too.
Forged wheels
Forged wheels start as a solid billet of aluminium that has been forged under very high pressure, which gives it a tight, uniform grain structure. The wheel is then machined from that single block. Because the material is so dense, a forged wheel can be made lighter than cast or flow-formed equivalents and still be very strong. Machining also gives a lot of freedom with the design and fitment.
SpeedWorks Forged wheels are:
- machined from a single block of 6061-T6 aluminium
- made to order, with a lead time of around 14 to 18 weeks
- secured with a 50% deposit, and non-refundable once ordered
- backed by a limited lifetime structural warranty.
Because each set is built to order, forged is the way to go when you want a specific size, offset or finish that isn't in the standard range. See the forged collection or message us to start a quote.
Side-by-side comparison
| Cast | Flow-formed | Forged | |
|---|---|---|---|
| How it's made | Molten aluminium poured into a mould | Cast face, barrel spun and rolled under pressure | Machined from a single forged 6061-T6 block |
| Relative weight | Heaviest of the three | Lighter than cast | Lightest for a given strength |
| Price | Most affordable | Mid-range | Highest |
| Availability | Off the shelf (SW range) | Off the shelf (SW range) | Made to order, ~14 to 18 weeks |
| SW examples | SW05, SW06, SW12, SW17, SW18 | SW01, SW02, SW09, SW15, SW16 | SpeedWorks Forged |
| Warranty | 12 months, materials and finish | 12 months, materials and finish | Limited lifetime structural |
All SW passenger wheels, whether cast or flow-formed, have the same 690 kg per-wheel load rating, a 73.1 mm centre bore and JWL, VIA and AS1638 certification. The 4x4 SW11 and SW21 are rated to 800 kg with a 110.1 mm bore.
Which should you choose?
Cast: style and value
Choose cast if you want a particular look, such as the deep-dish SW08 15x8 +15 for older JDM cars, the retro deep-lip SW17, or the 10-spoke SW12. Choose it too if you want the most wheel for the money. The SW12 18x9.5 +22 is one of the most popular fitments in our gallery. It's on Nissan Silvia S15s, 200SX S14s, Skyline R33 and R34s and Toyota Chaser JZX100s.
Flow-formed: lighter for daily and spirited driving
Choose flow-formed if you want to save weight without the cost and wait of forged. Customers run the SW16 19x8.5 +40 on Audi RS3 8V and VW Golf R builds, and the SW09 19x8.5 +35 on Golf Mk7, Mk7.5 and Mk8 GTIs.
Forged: made to your spec
Choose forged if you want the lightest, strongest option, or a size and finish built to your spec, and you're happy to wait for it.
Whichever you choose, fitment comes first. Check stud pattern, offset and brake clearance using our offset calculator, or ask us.
Frequently asked questions
Is flow-formed the same as forged?
No. A flow-formed wheel has a cast face and a barrel that has been pressure-formed. A forged wheel is machined entirely from a forged block. Flow-formed sits between cast and forged in both weight and price.
Are cast wheels safe?
Yes, when they're made and tested properly. Every SW cast wheel carries JWL, VIA and AS1638 certification and a 690 kg load rating per wheel, the same as our flow-formed wheels.
How long do SpeedWorks Forged wheels take?
Around 14 to 18 weeks, as they're made to order. A 50% deposit is required, and orders are non-refundable once placed.
Which SW wheels are flow-formed?
SW01, SW02, SW03, SW07, SW09, SW14, SW15, SW16, SW19, SW20 and SW22, plus the SW11 and SW21 4x4 wheels.