15×5.5″ Wheels for Mercedes-Benz 300SL Roadster

15×5.5″ wheel for the Mercedes-Benz 300SL Roadster (W198 II) represents a significant factory evolution. While the original 300SL Gullwing debuted with narrower 5″ wheels, the Roadster was upgraded to the 5.5″ width to accommodate the era’s new radial tire technology (specifically the Michelin X) and to civilize the car’s high-speed handling.

Listing Details

• Set of Four Bolt-On Wheels
• 15″ Diameter × 5.5″ Wide
• 4x Part #615A
• Two-Piece Steel & Alloy Construction
• For Mercedes-Benz W198 300SL Roadster
• Date Stamp 8-57

1. The Factory Standard: Kronprinz (KPZ)

The vast majority of 300SL Roadsters left the factory with steel-and-alloy wheels manufactured by Kronprinz (KPZ).

• Construction: A two-piece design featuring a forged steel center (for strength and bolt-on security) mated to a spun aluminum barrel.

• Dimensions: $15\times5.5\text{K}$ (The “K” denotes the specific hump/bead profile of the rim).

• Identification: Look for the KPZ logo and the specific Mercedes part numbers stamped near the lug holes.

  • Part #S615A: Common for early Roadster applications.

  • Part #6146A: Often seen on later replacement or service units.

• The “Disc Brake” Shift: After March 1961 (chassis 2780), the Roadster transitioned from drum to Dunlop disc brakes. While the 15×5.5″ dimensions remained standard, the wheel design was refined to ensure clearance for the new calipers.

2. The Exotic Option: Borrani Wire Wheels

While most Roadsters used the KPZ disc wheels with hubcaps, many owners opted for Borrani “Record” wire wheels for a more aggressive, sporting look.

• Design: Featuring 72 spokes and an aluminum rim, Borranis reduced unsprung weight by roughly 25% compared to steel wheels.

• Knock-offs: These require a splined hub adapter. Authentic sets feature the “Ruote Borrani Milano” stamping and the iconic three-eared spinners.

• Modern Note: Many Borranis found today are 1990s-era reproductions (Part #RW4466), which are highly sought after but distinct from 1950s originals.

3. Rudge Wheels: A Technical Distinction

It is a common misconception that the 300SL Roadster utilized the 15×5.5″ size for Rudge (knock-off) wheels.

• The Truth: Factory Rudge wheels were primarily a Gullwing-era option. While some early Roadsters were retrofitted or special-ordered with them, the move toward disc brakes in 1961 made the bolt-on 5.5″ wheel the definitive standard for the model’s later, more refined years.

4. 2026 Market Value

As 300SL Roadster values have stabilized well north of $1.3 Million, original wheels have become high-stakes collector items.

• Set of 4/5 KPZ Wheels (Original/Restored): $6,000 – $11,500. A “No Reserve” set of five recently sold on Bring a Trailer (mid-2025) for $11,500 due to their “NOS” (New Old Stock) condition.

• Set of Borrani Wire Wheels (With Hubs): $12,000 – $18,000 for a complete, ready-to-mount kit.

• Tire Pairing: For a period-correct look and feel, these wheels are almost exclusively paired with Michelin XWX or Pirelli Stella Bianca tires ($185/70\text{R}15$ or $185\text{R}15$).