PORSCHE 992 GT3 RS FITMENT & TIRE OPTIONS

The 992 GT3 RS is one of the most capable track cars ever produced. With 518 hp from the naturally aspirated 4.0L flat-six, a massive swan-neck rear wing generating 409 kg of downforce at 177 mph, and a suspension system derived directly from the 911 GT3 Cup car, this is a machine engineered for one purpose: destroying lap records. When upgrading to Grip Theory forged wheels, selecting the right diameter based on your brake system and intended tire is critical — the wrong combination can leave performance on the table or create clearance issues.

Quick Reference
Hub Type: Center Lock | Center Bore: 84mm | CL Torque: 450 Nm (332 ft-lb)
Hardware: Use a proper 90mm hex socket and calibrated torque wrench. Re-torque after 50–100 km of driving. Never use an impact gun on center lock hubs without a torque-limiting adapter.

PCCB (Carbon Ceramic Brakes) — 20" Mandatory

If your GT3 RS is equipped with the factory Carbon Ceramic Brakes (PCCB), you must run a 20-inch front and rear to clear the enormous brake calipers. The 410mm front rotors and their corresponding calipers simply cannot fit behind a 19-inch barrel. However, the 20-inch constraint is far from a limitation — the tire selection at 20 inches for this platform is exceptional.

01

20" PCCB Setup — Sizes & Tires

Running 20" with PCCB gives access to the best DOT-legal track tires on the market.

Recommended Front: 20x9.5 ET50
Recommended Rear: 20x12.5 ET48
Street Tires: 265/35R20 Front, 325/30R20 Rear
Track Day (200TW): 265/35R20 Front, 325/30R20 Rear

Recommended tire models for 20" PCCB:

Michelin Pilot Sport Cup 2 / Cup 2 R: The gold standard. Factory-spec tire with incredible dry grip and a predictable, progressive breakaway. The Cup 2 R adds a stiffer sidewall for more precise turn-in under high aero load.
Goodyear Eagle F1 Supercar 3R: Exceptional heat tolerance for multi-stint track sessions. Slightly more durable than the Cup 2 at the expense of marginally lower peak grip.
Nankang AR-1: A popular, durable R-compound option that delivers 90% of the Cup 2's grip at 60% of the cost. Ideal for dedicated track days where you'll burn through tires quickly.
Hoosier R7: D.O.T.-approved track tire for those chasing ultimate lap times without going to full slicks. Fastest DOT tire available in these sizes.

Steel Brakes (Iron Rotors) — 19" Unlocked

If your GT3 RS is equipped with factory steel (iron) brakes, you gain the ability to drop down to a 19-inch front and rear. This is the preferred setup for dedicated track cars and club racers because it unlocks the ability to run true motorsport slicks — which are primarily manufactured in 18" and 19" diameters for GT-class racing. The additional sidewall height also provides more tire deflection for curb compliance and protection against rim damage.

02

19" Steel Brake Setup — Slick Access

Running 19" is all about maximizing mechanical grip with real racing rubber.

Recommended Front: 19x9.5 ET50
Recommended Rear: 19x12.5 ET48
DOT Track Tires: 265/35R19 Front, 325/30R19 Rear
Slick Sizes: 265/660R19 Front, 305/680R19 Rear (confirm with tire manufacturer for specific compounds)

Recommended slick options for 19":

Pirelli P-Zero DH Slicks: The industry standard for GT racing. Used in Porsche Carrera Cup and GT3 Cup. Unmatched grip consistency and durability across multi-stint endurance events.
Michelin Pilot Sport Slicks: Factory spec for Porsche Carrera Cup. Incredible peak performance with a slightly narrower operating window than the Pirelli.
Yokohama Advan A005: A favorite among club racers for its durability and predictable, progressive breakaway characteristics. More forgiving than the Pirelli or Michelin at lower operating temperatures.

Why Diameter Matters on the GT3 RS

03

19" vs 20" — The Decision Framework

Choosing between 19" and 20" isn't just about brake clearance — it fundamentally changes the tire options and driving character of the car.

20" Advantages: More wheel face visibility, stiffer sidewall for higher aero loads, access to the best DOT-legal track tires (Cup 2, Supercar 3R). Best for: street/track cars, time trials, and cars running PCCB.
19" Advantages: Access to true slicks, more sidewall for curb compliance, slightly lower unsprung weight. Better for: dedicated race cars, endurance events, and club racing series that mandate DOT tires (where the AR-1 and R7 in 19" are faster than their 20" counterparts due to more sidewall flex).
Weight savings: A forged 19" wheel at this width can save 3–5 kg per corner versus the factory forged 20" option. On a car that generates 409 kg of downforce, reducing unsprung mass improves the suspension's ability to keep the tire planted over bumps at high speed — which directly translates to faster corner speeds.

Center Lock Note: Both 19" and 20" setups for the 992 GT3 RS are built to precise center-lock specifications to perfectly match the factory hubs. No spacers, adapters, or modifications are required. Every Grip Theory center-lock wheel is individually inspected for hub bore concentricity to ensure zero vibration at any speed.

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