TT Oversteer

Putting a set of sevens on the rear of my '77 911S. I did this on my '69T with 15x7's with no rubbing issues but haven't tried this with 16x7's and 225/50/16 tires. I don't really want to roll the fender lips but I guess I will if the fit is close. I know this is a pretty common mod and could use anyone's input on tire sizes and any other experience with this setup before I order tires and find out the hard way. Thanks!

911S3.6

The only way i could run 16x7 rears with 225/50-16 tires on my 1975 911S was running the 1986 951 turbo style 16x7s and I did have to roll the fender lips.

Nick

Edgy01

I don't think you'll have a fitment issue on the rear of a 1977 (narrow body). I successfully ran 7x15s on my 1977 911S many years ago with a more singificant sidewall tire (Pirelli CN36). The 225/5--16s should be no issue. Recall the the biggest conflict area on a earlier 911 is with the front left fender.

LaughaC

205's rubbed on mine...

TT Oversteer

I've got 205's on 16x6 wheels on there now and there's plenty of clearance. Were your 205's mounted on 16x7 wheels?

LaughaC

Yes. Sorry about my brief post. I now run 205's on 16x6 Fuchs with more clearance than I want.

The rubbing came when I ran 15x7's with 205s. I need a set of those much-sought '86 951 Fuchs.

TT Oversteer

OK, now I'm even more confused than before:

911S3.6 says 16x7's will rub unless they're from a '86 951.

Edgy had no issues but he ran 15x7's not 16x7's.

LaughaC had ussues with 15x7's with 205 tires let alone 215's.

I ran 205's on 15x7's on my old '69T with no issues.

So........am I to infer that 16x7 wheels have a different offset than 15x7 wheels or that the overall diameter of 16's with 50 series tires is larger than the diameter of 15's with 60 series tires? And that 16x7 951 wheels are unique from 911 wheels in their offset? I still think the fender width of a '69 car is the same as a '77 car. I'm thinking tires from different manufacturers vary in width and aspect ratio even though the tires are the same nominal size. Sometimes even simple things are complicated for me!!!!????

LaughaC

Tell me about it. This issue prompted me to try 40 series 205 tires.

I like the smaller diameter's improved gear ratio so I should try a set of 16x7 wheels (again). That will make the 4th set of Fuchs I've tried. (sigh)

911S3.6

I will preface by saying, when my car was a narrow body 1975 911s, box-stock, numbers matching from the Porsche factory, it had 6x15 fuchs (P/N 901.361.012.06) [ 36mm offset, 112mm backspace]on all four corners with 185/70-15 tires.
I wanted more footprint and ended up buying the 7x15(R) wheels used on the famous narrow body lightweight 911R (P/N 901.361.012.05). These wheels have an offset of 49mm and backspacing of 138mm.
With these i was able to run 215 series rear tires.
I sold these eventually and got the 7x16 fuchs from 1986 944 turbo (P/N 951.362.115.00)[23.3mmoffset. 138mm backspace] and ran these on all four corners- 205 fronts , 225's rear. I did roll the fenders in the rear because R-compound tires rubbed at cornering speeds on track.
When the car got seriously modded, i had to finally flare it to get 225 front , 255 rear.
FYI- 911 7x16 fuchs, (P/N 911.362.115.00) have 23.3mm offset and 112mm backspace.

Hope this helps,

Nick

Madpcar

I'm currently doing this at the moment - you will probably need to roll your lip (baseball bat method)and adjust the camber in 2 - 3 Deg - I have 16x7 with 225/50/16 on them(goodyears) on the rear. You need to look at tire selection as well - some tires may be 225 tread width but the side wall curve may very from manufacture and this can cause rubbing.
Hope I have not confused the issue !

TT Oversteer

Nick, thanks for the technical info on wheel sizes BUT your numbers don't make sense unless I am misunderstanding the definitions of "offset" and "backspacing". According to my understanding offset is the distance from the wheel's hub mounting surface and the centerline of the wheel i.e. equidistant point between the inner and outer bead surfaces. Backspacing is the distance between the hub mounting surface and the inner bead surface of the wheel. Here's the source of my confusion: How can you have the same offset (23.3mm 951 wheel; 23.3mm 16x7 911 wheel) with different backspacing when the two wheels being compared are the same width (7in.)?? The only way you could have two wheels with the same offset but different backspacing is if the wheels were of different widths. Or am I missing something here? Increasing offset puts the wheel closer to the center of the car and further from the fender bead (positive offset). Offset and backspacing increase and decrease by the same amount if the wheel width remains constant.

MillenniumFalcon

Bump.

Wondering how things ever resolved for you? Because now I am dealing with the same issue- a '75 911S with stock narrow rear fenders, 16x7 (late 80's) Fuchs with 23.3mm offset on the rear. With 225/50/16 tires mounted they hit the rear fender lip!

Did you find a good tire/camber setting combo to keep your 16x7's on the car, or did you change wheels?

Thanks, David

Charles Freeborn

Also interested in this topic - with a slight variation.
I run 205/60/15s on stock Fuchs on my '74. Fit perfectly.
I'd like to get a second set of inexpensive wheels (cookie cutters?) for 6 or so track days a year. I'd like to get 225/45/16's on the rear and 205/50/16's on the front. I do not want to change alignment setting when I switch back and forth.
Has anyone tried this combination and what wheel widths did you use?
Thanks.
-C

Bill Verburg

911 and 944 7x16 are almost the same wheel, these both have the same ET23.3, they both have the same bead width, 7", and the same flange width. So they place the tire in exactly the same place. The difference is in the hub design which allows the 944 version to accommodate larger rotors and calipers than the 911 version.

7ET23.3 fit on a n/b(non SC/Carrera flare car depends on the tire, taller and wider is tougher to fit than shorter and narrower, some side walls are more square others more tapered as well as ride height and suspension specs.

a tallish tire like a 215/60 x15 @~25.2" will hit most normal height 911 several inches up into the rear fender, a shorter 225/50 x15 @~23.9" would clear unless the car was extremely low

a 225/45 x16 on a 7 is going to be around 23.9" and will be easier to fit than a 225/50 x16 on a 7.

race911

Why staggered sizes? 225s on a 7X15 all the way around.

Changing tires/wheels has nothing to do with alignment.

What I ran on my stock(ish) class '73S ~15 years ago. Not stupid low, but did have 30mm torsion bars. Held 3 of 4 local track records at one time.