Porsche 911 / BMW M3 Forged Wheels – Design 3
Matte Silver Directional Milled
2018 Porsche 911 GT2 RS Wheels & Rims: Bolt Pattern, Offset & Sizes
Fitting Porsche 911 GT2 RS wheels? This page gives the 2018 Porsche 911 GT2 RS bolt pattern, centre bore, factory rim size and the offset range for aftermarket and forged Porsche 911 GT2 RS rims: the same spec sheet ANKUSI uses when machining forged wheels for this car.
Porsche 911 GT2 RS (2018): Porsche centerlock hub, 71.6mm center bore. Factory wheels: F: 20x9.5J R: 21x12.5J. Reference fitment ranges.
Bolt PatternCenterlock
Wheel Bolt/NutCentre-lock single nut (600 Nm, 3/4in drive)
Center Bore71.6mm
Wheel Load Rating700–850 kg/wheel (Performance / Sports Car segment reference)
Caliper TypeFixed 6-piston front caliper (OEM, Porsche GT/RS)
Year2018
CategoryTrack Sports Car
✓ Verified by ANKUSI's Engineering Team — IATF 16949 & ISO 9001 certified forged wheel manufacturer, TÜV/SFI/VIA compliant. See our factory & certifications →
Wheel Size & Offset at a Glance
| Configuration | Wheel Size & Offset |
|---|---|
| Flush Fitment | F 20x9.5J ET50 / R 21x12.5J ET48 |
| Maximum Aggressive | F 20x9.5J ET50 / R 21x12.5J ET48 |
How to Read Wheel Offset & Measurements
Use these two references before ordering: the left diagram shows where each spec (PCD, center bore, offset, width and diameter) is measured on the wheel; the right diagram shows how positive, zero and negative offset shift the wheel face relative to the hub centerline.
ANKUSI Engineering Expert Advice
On a track-focused car the factory already spent the unsprung-weight budget carefully, so the aftermarket brief is narrow: same footprint, less mass, more barrel clearance for the brake package. Chasing poke on a car like this usually costs lap time before it buys looks.
The Porsche 911 GT2 RS runs a Centerlock fitment, 71.6mm center bore, and a F: 20x9.5J wheel from the factory. Our Flush Fitment reference is F 20x9.5J ET50 / R 21x12.5J ET48 - on this car the published aftermarket guidance is that the factory footprint already sits flush. Our Maximum Aggressive reference is F 20x9.5J ET50 / R 21x12.5J ET48 - the verified data does not support going wider than the flush spec on this chassis.
Porsche 911 GT2 RS OE Wheel Specs
The 2018 Porsche 911 GT2 RS (Track Sports Car) runs a Centerlock hub with a 71.6mm register. Factory wheels are F: 20x9.5J R: 21x12.5J.
Why the factory spec works for most owners:
- Keeps unsprung weight low to preserve the factory handling balance
- Matches the wider, performance-oriented tire sizing typical of this platform
- Maintains clearance for the factory brake package and suspension geometry
- Balances grip with ride comfort for daily and spirited driving
ANKUSI builds these wheels — we are the forging factory, not a reseller. For the Porsche 911 GT2 RS (2018) we machine every wheel to the vehicle’s own hub dimensions on our own CNC line, so the wheel hub-centres on the car with no spacer rings, in whatever diameter, width and offset you specify.
Converting these ET figures to backspacing? Use the wheel offset and backspacing calculator.
The figures on this page are part of our open wheel fitment dataset — 6,436 vehicles, free to download, CC BY 4.0.
Flush Fitment
For a flush look with minimal rubbing, F 20x9.5J ET50 / R 21x12.5J ET48 is the recommended starting point on a stock or mildly lowered Porsche 911 GT2 RS.
Maximum Aggressive Fitment
F 20x9.5J ET50 / R 21x12.5J ET48 is a more aggressive reference setup. Beyond this, expect rubbing under compression without fender rolling or camber correction.
Real-World Fitment Notes
the aftermarket route is buying centerlock forged wheels directly (Forgeline GT1/GE1/GA1R centerlock, APEX VS-5RS/EC-7RS centerlock, HRE) — NOT a bolt-on adapter conversion centerlock torque spec is critical; brand wheels ship with a matched centerlock nut/spline (data from same 991.2 GT centerlock platform)
5-Tier Configuration Options
A Factory-Style F 20x9.5J ET50 / R 21x12.5J ET48
Recommended setup: F 20x9.5J ET50 / R 21x12.5J ET48 | Economy impact: Negligible | Best for: Daily commuting, family use
Appearance: 7/10 | Comfort: 9.5/10 | Install difficulty: ★☆☆☆☆
Estimated cost: $450-800 (wheels + tires + install)
B Comfortable Upgrade F 20x9.5J ET50 / R 21x12.5J ET48
Recommended setup: F 20x9.5J ET50 / R 21x12.5J ET48 | Economy impact: -2 to -4% | Best for: Daily / street
Appearance: 8/10 | Comfort: 9/10 | Install difficulty: ★☆☆☆☆
Estimated cost: $1,950-2,550 (wheels + tires + install)
C Balanced / Flush Fit F 20x9.5J ET50 / R 21x12.5J ET48
Recommended setup: F 20x9.5J ET50 / R 21x12.5J ET48 | Economy impact: -4 to -6% | Best for: Street
Appearance: 8.5/10 | Comfort: 8/10 | Install difficulty: ★★☆☆☆
Estimated cost: $2,600-3,400 (wheels + tires + install)
D Aggressive F 20x9.5J ET50 / R 21x12.5J ET48
Recommended setup: F 20x9.5J ET50 / R 21x12.5J ET48 | Economy impact: -6 to -9% | Best for: Show / occasional track
Appearance: 9/10 | Comfort: 6.5/10 | Install difficulty: ★★★☆☆
Estimated cost: $3,900-5,000 (wheels + tires + install)
E Max Aggressive F 20x9.5J ET50 / R 21x12.5J ET48
Recommended setup: F 20x9.5J ET50 / R 21x12.5J ET48 | Economy impact: -8 to -12% | Best for: Show only
Appearance: 9.5/10 | Comfort: 4/10 | Install difficulty: ★★★★☆
Estimated cost: $4,800-6,200+ (wheels + tires + install)
Performance Comparison Matrix
| Metric | Tier A | Tier B | Tier C | Tier D | Tier E |
|---|---|---|---|---|---|
| Wheel Spec | F 20x9.5J ET50 / R 21x12.5J ET48 | F 20x9.5J ET50 / R 21x12.5J ET48 | F 20x9.5J ET50 / R 21x12.5J ET48 | F 20x9.5J ET50 / R 21x12.5J ET48 | F 20x9.5J ET50 / R 21x12.5J ET48 |
| Economy Impact | Negligible | -2 to -4% | -4 to -6% | -6 to -9% | -8 to -12% |
| Appearance | 7/10 | 8/10 | 8.5/10 | 9/10 | 9.5/10 |
| Comfort | 9.5/10 | 9/10 | 8/10 | 6.5/10 | 4/10 |
| Install Difficulty | ★☆☆☆☆ | ★☆☆☆☆ | ★★☆☆☆ | ★★★☆☆ | ★★★★☆ |
| Cost Range | $450-800 | $1,950-2,550 | $2,600-3,400 | $3,900-5,000 | $4,800-6,200+ |
| Best For | Daily commuting, family use | Daily / street | Street | Show / occasional track | Show only |
Real-World Reference Cases
The examples below are compiled from typical ANKUSI customer configurations and are labeled as reference cases, not individually verified real-world builds.
Case 1: Daily Driver (Factory-Style)
Profile: Everyday driving, prioritizes comfort and low running cost.
Setup: F 20x9.5J ET50 / R 21x12.5J ET48
Cost: ~$620
Outcome: Minimal visual change, ride and fuel economy essentially unaffected.
Case 2: Balanced Enthusiast (Balanced / Flush Fit)
Profile: Wants a sportier stance without sacrificing daily usability.
Setup: F 20x9.5J ET50 / R 21x12.5J ET48
Cost: ~$3,000
Outcome: Noticeable visual upgrade, fuel economy drop within the expected range.
Case 3: Show Build (Max Aggressive)
Profile: Built primarily for shows or occasional track/show use.
Setup: F 20x9.5J ET50 / R 21x12.5J ET48
Cost: ~$5,500
Outcome: Maximum visual impact; daily comfort and fuel economy are heavily compromised, physical test fit required before production.
Decision Guide
1
What's your primary use? Daily commuting → Tier A/B. Weekend street driving → Tier B/C. Show or occasional track use → Tier D/E.
2
What's your budget? Under $800 → Tier A. $800-3,400 → Tier B/C. $3,400+ → Tier D/E.
3
How much does fuel economy matter? Very important → Tier A. Somewhat important → Tier B/C. Not a priority → Tier D/E.
4
Still unsure? Tier C (Balanced / Flush Fit) is the default choice for most Porsche 911 GT2 RS owners.
Offset & Backspacing Reference
Backspacing is calculated as wheel width (in) ÷ 2 + offset (mm) ÷ 25.4 + 0.5 (flange allowance):
- OE: F 20x9.5J ET50 → ~7.22″ F backspacing, R 21x12.5J ET48 → ~8.64″ R backspacing
- Flush: F 20x9.5J ET50 → ~7.22″ F backspacing, R 21x12.5J ET48 → ~8.64″ R backspacing
- Max: F 20x9.5J ET50 → ~7.22″ F backspacing, R 21x12.5J ET48 → ~8.64″ R backspacing
A Note on Clearance
Final clearance depends on the exact tire model, suspension height, brake package, alignment and vehicle tolerances. A physical test fit is recommended before production.
Want to check a different width or offset before you order? Use our Offset & Backspacing Calculator to solve the numbers yourself, or looking for your exact Porsche spec, or want a wheel built to a custom offset for your Porsche 911 GT2 RS? Contact ANKUSI with your bolt pattern and offset target and we will confirm the correct forged wheel spec for your build.
Custom Forged Wheels for the Porsche 911 GT2 RS (2018)
Everything above is reference data. If you want wheels actually built to it, that is what ANKUSI does: we are a forged wheel factory in Guangzhou, China, IATF 16949 and ISO 9001 certified, forging on our own 10,000-ton press and producing over 120,000 wheels a year. Forging blank, CNC machining, finishing, coating and inspection all happen in the same building — nothing is subcontracted and nothing is relabelled from another manufacturer.
Every set is cut to order. Diameter, width, offset, concavity, monoblock or multi-piece construction and the finish are all yours to choose.
We do not hold this pattern wheels on a shelf — they are forged to order, which is why any offset, width and bore combination on this page is buildable rather than limited to a stock list.
Frequently Asked Questions
What is the biggest wheel size I can fit on my Porsche 911 GT2 RS without rubbing?
The most aggressive fitment we recommend without fender work is F 20x9.5J ET50 / R 21x12.5J ET48. Going beyond this typically causes rubbing under compression unless you roll the fenders or add camber correction.
What does a flush wheel fitment look like on the Porsche 911 GT2 RS?
For a flush look with minimal to no rubbing, we recommend F 20x9.5J ET50 / R 21x12.5J ET48 as a starting point on a stock or mildly lowered Porsche 911 GT2 RS.
Do I need wheel spacers for my Porsche 911 GT2 RS?
No. ANKUSI forges each wheel to your exact target offset, including the flush or max specs above, so you get the correct fitment without stacking spacers. Spacers are typically only used to push out an existing OE-offset wheel without replacing it, which isn't necessary when you're ordering a custom-offset forged wheel.
How do I calculate wheel backspacing for my Porsche 911 GT2 RS?
Backspacing (in inches) = wheel width (in) ÷ 2 + offset (mm) ÷ 25.4 + 0.5 (flange allowance). For example, the flush spec above works out to roughly 7.22" backspacing up front and 8.64" in the rear.
What's the difference between wheel offset and backspacing?
Offset is the distance in millimeters from the wheel's true centerline to its mounting face (positive offset pulls the wheel in, negative pushes it out). Backspacing is the distance in inches from the mounting face to the back edge of the wheel barrel. They describe the same fitment from two different reference points, which is why ANKUSI lists both above — some shops and tuning guides quote offset, others quote backspacing.
Can I run staggered wheels (different sizes front and rear) on my Porsche 911 GT2 RS?
Yes — the Porsche 911 GT2 RS's factory and our recommended flush/max fitments already use staggered sizing (different width front and rear), and ANKUSI can forge matching staggered sets to your target offsets.
Forged Wheel Designs for the Porsche 911 GT2 RS
Every design below is forged to order, so it can be machined to the Porsche 911 GT2 RS's bolt pattern, with the width and offset calculated for your setup.
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