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Porsche Cayman & Boxster Wheel Fitment Guide: Why 911 Wheels Sit Wrong on a Mid-Engined Car

Illustrated Porsche Cayman/Boxster sports car, JP-Time.Club house-style artwork

Introduction

The Cayman and Boxster share their bolt pattern, hub bore and lug hardware with the 911. That fact sells a lot of wrong wheels. A 911 wheel will bolt onto a Cayman without complaint — and then sit in completely the wrong place, because the two cars were designed around opposite rear-axle geometry. This guide covers the verified factory specifications for the Cayman 987 and Boxster 981, and explains exactly where the 911 comparison breaks down.


Section 1: OEM Wheel Specifications

Both cars share the same core hardware: 5×130 bolt pattern, 71.6 mm hub bore, M14 lug bolts, 130 Nm torque. Like all modern Porsches they are staggered front to rear.

Porsche Cayman 987 & Boxster 981 — OEM Staggered Wheel Specifications
Model Generation Years Variant Front Wheel Rear Wheel Front / Rear Tyre
Cayman 987 (facelift) 2009–2013 2.9 7Jx17 ET55 8.5Jx17 ET40 205/55R17 · 235/50R17
Cayman 987 (facelift) 2009–2013 S 3.4 8Jx18 ET57 9Jx18 ET43 235/40R18 · 265/40R18
Cayman 987 (facelift) 2009–2013 R 3.4 8.5Jx19 ET55 10Jx19 ET42 235/35ZR19 · 265/35ZR19
Boxster 981 2012–2017 2.7 8Jx18 ET57 9Jx18 ET47 235/45R18 · 265/45R18
Boxster 981 2012–2017 S 3.4 8Jx19 ET57 9.5Jx19 ET45 235/40ZR19 · 265/40ZR19
Boxster 981 2012–2017 GTS 3.4 8Jx20 ET57 9.5Jx20 ET45 235/35ZR20 · 265/35ZR20

The number that matters is the rear offset. Across every variant above, the rear axle runs ET40 to ET47. Compare that with the 911: the 997 Carrera runs ET58 at the rear, and the 991.2 Carrera runs ET77. Same 5×130 pattern, same 71.6 mm hub — but up to 37 mm of difference in where the wheel actually sits.

This is a geometry consequence, not a styling choice. The 911 carries its engine behind the rear axle and pulls the wheel inboard with a high offset. The Cayman and Boxster are mid-engined, and their rear wheels sit much further outboard. Any wheel sold as “fits Porsche 5×130” without an offset figure is a wheel you cannot evaluate.


Section 2: Recommended Fitment Ranges

Porsche Cayman and Boxster offset comparison diagram

Factory-Faithful

Front: ET55–ET57. Rear: ET40–ET47. These are the verified factory figures for the variants in the table above.

  • Front stays high, rear stays low. That split is consistent across 17, 18, 19 and 20-inch fitments
  • Widths are modest by modern standards — 7J to 8.5J front, 8.5J to 10J rear. These are light cars and the factory did not need extreme sections
  • Buy staggered sets. A square set of four will sit wrong at one end of the car

Aftermarket Fitment

  • 911 wheels are the classic mistake. They bolt on. They will tuck too far inboard at the rear, especially anything from a 991
  • Spacers are a legitimate tool here, but because Porsche uses bolts rather than studs, any spacer requires correctly lengthened bolts with full thread engagement. This is a safety item
  • Load rating is rarely the constraint on these cars — they are light. Clearance and offset are what limit you
  • These ranges describe factory practice. Anything beyond them should be measured on your own car

Instagram Search Keywords

Post counts verified July 2026:

Model Tags:
- #PorscheCayman (618K)   #PorscheBoxster (361K)
- #Caymans (169K)         #BoxsterSpyder (39K)

Chassis Tags:
- #987Cayman (34K)        #981Boxster (23K)

Wheel Brand Tags:
- #BBSWheels (1.1M)  #RAYSWheels (776K)
- #WORKWheels (1.9M)

Section 3: Selection Tips and Cautions

  • 5×130 with a 71.6 mm hub bore. Shared with the 911 and Cayenne — but offset is what decides fitment, not the pattern
  • Lug bolts, not studs. M14. There is nothing to hang the wheel on while you align it, and bolt length must be recalculated whenever wheel thickness or spacers change
  • 130 Nm torque. Use a torque wrench — the threads are in the hub, and stripping them is expensive
  • Centre-lock wheels exist on some Porsche models. Those are a completely different mounting system with a 101 mm hub and no bolt pattern at all. Nothing in this guide applies to them
  • Brake clearance. The Cayman R and Boxster GTS carry larger brakes — verify before dropping to 17 or 18-inch

Fitment verification checklist:

  • ✓ Confirm the offset for each axle, not just the bolt pattern
  • ✓ Confirm the wheel is not a 911-specific high-offset rear
  • ✓ Confirm bolt length and seat type, especially with spacers
  • ✓ Check caliper clearance before reducing diameter
  • ✓ Confirm the car is bolt-on, not centre-lock

Conclusion

The Cayman and Boxster are straightforward cars to fit wheels to, provided you stop treating “5×130” as the answer. Front offsets sit around ET55–57 and rear offsets around ET40–47, and that rear figure is what separates these cars from the 911 they share a bolt pattern with. Work axle by axle, and treat any listing without an offset as incomplete information.

Looking for genuine 5×130 staggered sets from Japan? Submit a Request and we will search our networks in Japan for the sizes and offsets you need.


Seen on the road

Which wheels are you looking for? Tell us the wheel, the size and the fitment — send us a request and we will go and find it.

Cayman/Boxster on BBS wheels — tagged #bbswheels by the owner.

Wheel identification is taken from the hashtags the owner applied to their own post.

Every guide in this series is built the same way: verified factory specifications, an offset diagram, and an honest account of what fits and what does not.

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