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Definitive Answer: Wheel Offsets on a Wide Bodied 1977

Looking to buy 9&11 x 17's for a 77 Turbo flared short hood 911. Searched and read and read and searched, talked to vendors, and the answers are all over the place. I am thinking either "Fuchs" or Magnus Walker/Fifteen 52 Outlaw wheels, not that I know if the brand matters. My intention on tires is 315 rears and 245 fronts but that may change. Does anyone have the definitive answer on the wheel specs from experience?

Last edited by MotoV; 11-09-2018 at 10:54 AM.. Reason: Because I couldn't stand looking at my spelling error.
Old 11-08-2018, 09:50 AM
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Bill Verburg is the resident wheel expert ... he should be able to give you the proper information !
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Old 11-08-2018, 09:55 AM
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My turbo bodied '86 should be the same fitment as your car.

I run Fikse wheels with Toyo R888 tires for wet on the track
17x9 front, back spacing 4.75" with 255/40-17
17x11 rear, back spacing 4.75" with 315/35-17
With my -3 degrees camber in the rear, I still have enough room for a 6mm spacer.

For dry track I run Fikse wheels with Hoosier R7 tires
17x9 front, back spacing 4.5" with 245/40-17
17x11 rear, back spacing 4.75" with 295/35-17 and 8" spacer

I sized my wheels so I could fine tune with thin hubcentric spacers if needed. If you have too much outer lip, there's nothing you can do, but if you have a bit too much back spacing it's easy to add good hubcentric spacers as long as you have long enough studs.

Hope that helps
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Old 11-08-2018, 10:23 AM
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Quote:
Originally Posted by 175K911 View Post
My turbo bodied '86 should be the same fitment as your car.

I run Fikse wheels with Toyo R888 tires for wet on the track
17x9 front, back spacing 4.75" with 255/40-17
17x11 rear, back spacing 4.75" with 315/35-17
With my -3 degrees camber in the rear, I still have enough room for a 6mm spacer.

For dry track I run Fikse wheels with Hoosier R7 tires
17x9 front, back spacing 4.5" with 245/40-17
17x11 rear, back spacing 4.75" with 295/35-17 and 8" spacer

I sized my wheels so I could fine tune with thin hubcentric spacers if needed. If you have too much outer lip, there's nothing you can do, but if you have a bit too much back spacing it's easy to add good hubcentric spacers as long as you have long enough studs.

Hope that helps
Ed,
Thanks for that info. Are you 100% sure the 77 and 86 setup would be the same? I heard other information in my searches.
Also do you know how backspace translates to offset? It seems like the wheel manufacturers want that info.
Old 11-08-2018, 10:54 AM
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The front hubs on a '77 are 1" more inset than those of a Carrera.
Back spacing depends on if you plan to use spacers and 930 wheels or deeper dish custom wheels.
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Old 11-08-2018, 10:55 AM
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Quote:
Originally Posted by RarlyL8 View Post
The front hubs on a '77 are 1" more inset than those of a Carrera.
What differences are there in the '77 front end assembly vs. a Carrera to make this 1" inset? The actual hub itself is the same part number in both the '77 PET and the '86 PET. Both are listed as 911.341.065.06. Both have the same A-arm as well. The only other thing that would affect placement of the wheel would be the strut/spindle.


offset = backspacing minus half of overall wheel width (outer rim edge to inner rim edge, not tire bead seat to bead seat)

edit: reversed/re-wrote my offset definition to ensure the subtraction results in proper (+,-) sign for positive or negative offset
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Last edited by KTL; 11-08-2018 at 11:25 AM.. Reason: reversed/re-wrote my offset definition
Old 11-08-2018, 11:18 AM
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Quote:
Originally Posted by KTL View Post
What differences are there in the '77 front end assembly vs. a Carrera to make this 1" inset? The actual hub itself is the same part number in both the '77 PET and the '86 PET. Both are listed as 911.341.065.06. Both have the same A-arm as well. The only other thing that would affect placement of the wheel would be the strut/spindle.


offset = backspacing minus half of overall wheel width (outer rim edge to inner rim edge, not tire bead seat to bead seat)

edit: reversed/re-wrote my offset definition to ensure the subtraction results in proper (+,-) sign for positive or negative offset
All 911 from at least '69 have the same hub o/s and will p;ave the wheels in the same place

The 930 from '75 thru '81 used the 911 hub w/ a removable 21mm spacer
930 from ~mid '81 used a different hub w/ integral spacer, thes moved the wheel out 21mm.

Similarly in back only those cars that have the turbo trailing arms have the wheel pushed out, that would be turbo and T/L
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Old 11-08-2018, 11:40 AM
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Quote:
Originally Posted by MotoV View Post
Looking to buy 9&11 x 17's for a 77 Turbo flared short hood 911. Searched and read and read and searched, talked to vendors, and the answers are all over the place. I am thinking either "Fuchs" or Magnus Walker/Fifteen 52 Outlaw wheels, not that I know if the brand matters. My intention on tires is 315 rears and 245 fronts but that may change. Does anyone have the definitive answer on the wheel specs from experience?
It's going to be tough to provide an answer because there are so many idiosyncratic variables involved.

For one steel vs f/g can make a difference, for another when a steel flare is hung though they might all start out the ame the specific way it is attached can make a difference.

The consensus for all 911 suspension w/ no spacers seems to be for the 9" front ET13 +/- and for the 11" rear ET-8 +/- w/ 255/40 & 315/35 tires
9ET13 has a f/s of ~4.49" and b/s of ~5.51
11ET-8 has a f/s of ~6.31 and b/s of ~5.69


175k911s above are, which seem quite aggressive
9ET-6.35 and 9 Et-12.7
11ET -31.75

Just as a starting point the max f/s on an SC/Carrera will be ~3.5" in front and 4.5" in back, so if the fenders allow 2" more wheel 930 fenders max fs should be ~5.5" and 6.5" but as I noted in the beginning each install will be a bit different.

The best thing to do is install wheels w/ a known f/s then measure

b/s won't be a limiting issue
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Old 11-08-2018, 01:56 PM
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Quote:
The 930 from '75 thru '81 used the 911 hub w/ a removable 21mm spacer
930 from ~mid '81 used a different hub w/ integral spacer, thes moved the wheel out 21mm.
I'm sorry, 930 not Carrera had the hub width change after 1980. I've swapped wheels on so many widebodies it gets to be a blur. Most of the wheels I've used had 5.5" back spacing front and 6.5" rear. I like to use spacers to place the wheel/tire combo exactly where I want it in the well as the available space on each side is not the same. If you are wanting to use no spacers the width becomes critical as well as the tire size and brand.
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Old 11-08-2018, 04:40 PM
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Here's a graphic that shows what pairs of a particular tire line will work best, The closer in height w/ some stagger that will depend on the motor/gearing

This is for Sumitomo HTR-Z tires 225/45 x17 & 255/40 x17 are a good match, similarly 245/45 & 315/35 or 275/40 & 315/35 are good matches.
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Old 11-09-2018, 06:11 AM
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Any wheel manufacturer that is building 9&11x17s for widebody 911 should know exactly what backspacing is needed for 911 with 930 flares, early 930 or late 930, with or without factory spacers. To get the exact answer to your question you have to decide what look you are after, deep or shallow dish, with or without spacers.
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Old 11-09-2018, 06:32 AM
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Bill is correct, my wheels are aggressive. But it was what was recommend to me by people who know these Fikse wheels on wide body 911’s. I played with various inner and outer rim shells to get what I wanted. Plus my disclaimer that I run -3 degrees camber. If I ran say -1 degree in the rear I’d need to remove the 6mm spacers.
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Old 11-09-2018, 07:03 AM
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Thanks to all for the responses. So I see there just is no definitive answer at the very least for a non-factory wide bodied car. Rather than just order and hope I will take Bill's advice and I will set about measuring my car using "a set of wheels with a known f/s" and see what I come up with. I guess the rims should be 17" for this to be accurate? Also I hate to ask but what does f/s stand for?
lol
Old 11-09-2018, 10:53 AM
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Front Spacing

Here is a picture of my old Red Rocket (1979 911SC with 930 fenders) with 9&11.5x17 Kodiaks with 245/315 combo.
The back spacing on the front was 5.5", back spacing on the rear was 6.5". This car would have the same suspension wheel locations as your '77. I used no spacers on the front and 1" spacers on the rear.
As Bill stated it is best to see exactly what you have on the individual car by extrapolating from known wheels. I did that for this one and all the others. The 9&11 combo is really safe with lots of room to move around, if you go bigger than that you get into left/right fender room variations and have to measure very carefully all the obstacles such as oil lines and alignment bolts.


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Old 11-09-2018, 11:33 AM
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Quote:
Originally Posted by MotoV View Post
Thanks to all for the responses. So I see there just is no definitive answer at the very least for a non-factory wide bodied car. Rather than just order and hope I will take Bill's advice and I will set about measuring my car using "a set of wheels with a known f/s" and see what I come up with. I guess the rims should be 17" for this to be accurate? Also I hate to ask but what does f/s stand for?
lol
Here's a comparison of an aggressive SC/Carrera fitment, 8ET25 & 9.5ET19 w/ 225/45 & 255/40 x17 to a wide body fitment, 9ET-3 & 11ET-8 w/ 245/45 & 315/35 x17

As you can see the front f/s(frontpace or how far the wheel sticks out is increased by +1.3" and the rear f/r is increased by +1.8, The apx. increase in fender width for either end in <2" by using the 930 fenders on the same chassis, also of note is the ~25lb-ft of torque loss due to the change. Another item of concern is the increase in scrub radius from an already high value by 28mm

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Old 11-09-2018, 11:55 AM
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From this thread:

Quote:
Originally Posted by JeremyD View Post
My wheels offsets are:

9 x 17 ET 17
11 x 17 ET -8


Tires on the picture are Nitto NT05 - 255/40/17 in the front 315/30/17 in the rear - but really Jeff Alton is the guy to talk to about wheels and offsets. I probably have room for a 9 x 17 with a 10 or 11 offset in the front -

Here are my zuffenhaus fuchs (same offset)


and my true design wheels



My car has a stock suspension (SC/Carrera) no spacers
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Old 11-10-2018, 05:25 AM
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Hey MotoV- don’t know where you live, but if you’re anywhere near Chicago, you’re welcome to borrow my wheels and tires to try on your car. That’s honestly the best way to be certain. Ed
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Old 11-10-2018, 06:01 AM
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