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Offset Rule

Josh Chambers

Active member
Joined
16 Jan 2004
Messages
34
Once upon a time, a young man dreamt of owning a 993 so he saved and saved until he had enough pennies to buy dream car, he found the perfect 993 C2 Narrow Body and purchased it on the spot.

Problem, young man start spending money to improve the look, so out went the all the stand spec lens and replaced with clear lens, exhaust upgrade, sound pack, etc….

Never happy with the 17” cup alloys, he decided to buy some 18” Turbo “look” alloys. Then the nightmare begins…. OFFSET!!! rule.

The book says offset (ET) = 65. The wheels I’ve purchased are ET= 52.

Will they fit? some supplier say they do and other say they won’t. I tried them on my car and they seem ok, but the wheel arch is flush on the wheel edge, concerning the outside of the tire will rub against the arch.

Any suggestions, I hear a few sites offering offset adjustment…is that recommended/safe?

As anyone experience this type of service?

Let’s hope this story has a happy ending, which doesn’t cost me a fortune!


Migration info. Legacy thread was 15292
 
Without getting too technical, incorrect offset will alter suspension geometry, which in turn will effect how a car handles. I would suggest going to a specialist with expert knowledge of suspension set up like Parr or JZ Machtech.

Migration info. Legacy thread was 15313
 

911 / 911 C4


Standard Wheels


Exclusive Wheels


Tequipment


Carrera17 x 7 (55)

17 x 9 (55)


XRB Sport Classic II18 x 7.5 (50)

18 x 10 (65)


Carrera17 x 7 (55) Part No. 996 362 124 00

17 x 9 (55) Part No. 996 362 128 00





XRL

Sport Design18 x 7.5 (50)

18 x 10 (65)


Cup Design17 x 7 (55) Part No. 965 362 124 00/01

17 x 9 (55) Part No. 965 362 128 00



413

Turbo Look18 x 7.5 (50)

18 x 10 (65)


Cup Design ‘9317 x 7 (55) Part No. 993 362 124 00

17 x 9 (55) Part No. 996 362 128 00




Targa17 x 7 (55) Part No. 993 362 124 5017 x 9 (55) Part No. 993 362 128 50


Carrera 417 x 7 (55) Part No. 996 362 124 01

17 x 8.5 (50) Part No. 996 362 128 01


Sport Classic17 x 7 (55) Part No. 993 362 124 51

17 x 9 (55) Part No. 993 362 128 51


Turbo18 x 7.5 (50) Part No. 993 362 134 05

18 x 8 (52) Part No. 993 362 136 00

18 x 10 (65) Part No. 993 362 140 01


Turbo Look18 x 7.5 (50) Part No. 993 362 134 06

18 x 8.0 (52) Part No. 993 362 136 01

18 x 10 (65) Part No. 993 362 140 04


Sport Classic II18 x 7.5 (50) Part No. 993 362 134 55

18 x 8.0 (52) Part No. 993 362 136 50

18 x 10 (65) Part No. 993 362 140 50


Sport Design18 x 7.5 (50) Part No. 996 362 134 55

18 x 8 (52) Part No. 996 362 136 50

18 x 10 (65) Part No. 996 362 140 50


Migration info. Legacy thread was 15323
 

SPORTDESIGN WHEEL


The SportDesign wheel is a two-piece wheel made to fit the Boxster, 993 and 996 models. The wheel features ten spokes for increased strength with large openings for effective brake ventilation and uses titanium bolts to connect the spokes to the rim section. Two sizes are available for the front — 7.5x18 in. or 8x18 in. and two for the rear — 9x18in. and 10x18in.


design_wheel.jpg



















7.5Jx18 in. (50 mm offset) for 986 (from MY 1998) and 996 models, frontPart No. 996 362 134 55

8Jx18 in.

(52 mm offset) for 993 (from MY 1996) models, frontPart No. 996 362 136 509Jx18 in. (52 mm offset) for 986 models (from MY 1998), rearPart No. 996 362 138 5010Jx18 in. (65 mm offset) for 993 (from MY 1996) & 996 models, rearPart No. 996 362 140 50

Recommended tires:
7.5 x 18 in.
225/40 ZR 18
8 x 18 in.
255/40 ZR 18
9 x 18 in.
265/35 ZR 18
10 x 18 in.
265/35 ZR 18

Note: For 993 Carrera 4S and Turbo, spacers must be used on the rear (2x25 mm) with 285/30 ZR 18 tires



Migration info. Legacy thread was 15324
 

classic_wheel.jpg

















SPORTCLASSIC II WHEEL


Designed to fit the Boxster, 993 and 996 models, the SportClassic II is a two-piece wheel with the same styling used on the 911 (996 model) Supercup. The wheel features ten spokes for increased strength, and uses titanium bolts to connect the spokes to the rim section. Two sizes are available for the front — 7.5x18 in. or 8x18 in. and two for the rear — 9x18in. and 10x18in.


7.5Jx18 in. (50 mm offset) for 986 (from MY 1998) and 996 models, frontPart No. 993 362 134 558Jx18 in. (52 mm offset) for 993 (from MY 1996) models, frontPart No. 993 362 136 509Jx18 in. (52 mm offset) for 986 models (from MY 1998), rearPart No. 993 362 138 5010Jx18 in. (65 mm offset) for 993 (from MY 1996) & 996 models, rearPart No. 993 362 140 50

Recommended tires:
7.5 x 18 in.
225/40 ZR 18
8 x 18 in.
255/40 ZR 18
9 x 18 in.
265/35 ZR 18
10 x 18 in.
265/35 ZR 18

Note: For 993 Carrera 4S and Turbo, spacers must be used on the rear (2x25 mm) with 285/30 ZR 18 tires

Migration info. Legacy thread was 15325
 

BOXSTER / BOXSTER S


Standard Wheels


Exclusive Wheels


Tequipment


Boxster Design16 x 6 (50)

16 x 7 (40)


396 Boxster Design*17 x 7 (55)

17 x 8.5 (50)


Carrera Wheel17 x 7 (55) Part No. 993 362 124 00

17 x 8 (50) Part No. 993 362 126 0


Boxster Design*17 x 7 (55)

17 x 8.5 (50)


XRA Sport Classic17 x 7 (55)

17 x 8.5 (50)


Dyno Wheel17 x 7 (55) Part No. 993 362 124 50

17 x 8.5 (50) Part No. 993 362 126 55


XRH Dyno Wheel17 x 7 (55)

17 x 8.5 (50)


Sport Classic17 x 7 (55) Part No. 993 362 124 51

17 x 8.5 (50) Part No. 993 362 126 55


413 Turbo Look18 x 7.5 (50)

18 x 9 (52)


Turbo**18 x 7.5 (50) Part No. 993 362 134 05

18 x 9 (52) Part No. 993 362 138 00


Turbo Look**18 x 7.5 (50) Part No. 993 362 134 06

18 x 9 (52) Part No. 993 362 138 01


Sport Classic II**18 x 7.5 (50) Part No. 993 362 134 55

18 x 9 (52) Part No. 993 362 138 50


Sport Design**18 x 7.5 (50) Part No. 996 362 134 55

18 x 9 (52) Part No. 996 362 138 50


* Standard Boxster S wheel ** From MY98 on


Migration info. Legacy thread was 15326
 
Josh

are all your new alloys et52 if so then you have a tweo sets of fronts!

I have been told to stick to the recommended offsets as above

Migration info. Legacy thread was 15345
 
If you have ET52 offset rims front & rear then you have Boxster rims (as per Peter's post).

Further to my post, altering wheel offset only becomes critical to geometry on the front (ie with regards to steering), although you may find clearances issues on the rear.

Altering the wheel offset will effect the steering axis in relation to the tyre contact patch. A difference of a few millimetres can be enough to alter the offset from negative to positive with inherent handling issues effecting steering feel and self alingment. However, as the fronts you have are the reccommended offset then all should be fine & dandy.

Migration info. Legacy thread was 15347
 
I have ET 50 at the front (as recommanded by manual) and ET 52 at the back (manual recommands ET65)

Migration info. Legacy thread was 15355
 

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