Anyone in Chicago with 16x7s on the front that I could use to check for fitment on?
 

I'd like to put 7s and 8s on my car, but it's lowered quite a bit. It's also corner-balanced, feels great, and I've never had to touch it in almost a decade, and I'd rather not mess with ride height if I don't have to.

I've done the math, and it's tight, so it could go either way rubbing the front fender lip or not. Best way to get the definitive answer is to see if I could find someone local with a set they'd let me throw on for five or ten minutes, is mount them, check for static contact through the range of steering lock, and then drive around the neighborhood to check for clearance at lock and under braking. It's worth asking!

w/ 205/55 x176 it is tight, 205/50 alleviates that The shorter tire OD does miracles

other helpful things to do: shave the fenders lips and use a bit more neg camber .

Unfortunately, I'm not anywhere near Chicago. But I run 16x7s with Michelin Sport AS3+ 205/55-16 at all 4 corners on my 1973. I don't have interference. Your SC should have no less clearance than my car.

The brand of tire also makes a difference, as some "205" are a little rounder or more square at the shoulder than others.

Running a 205/50 would also drop the front end slightly (1/4"?) with no change in geometry. This is what I would do if I was changing my wheels and tires and did not care whether I could rotate the tires from front to rear.

You must have missed this
There is a long history of folks w/ 7x16 205/55 having clearance issues when the cars are lowered at all

do a search if you don't want to believe me

I’ll go take ride height measurements when I’m home again. Was meaning to do that and look up my alignment settings etc and contribute to the setup thread.

Photo for ride height reference

http://forums.pelicanparts.com/uploa...1718240519.jpg

I'm in Des Plaines and coincidentally I have an 87 with 16's on it in my garage. It's not my car. This particular car rides very low and there is lot of evidence of inner wheel well rubbing. One of the things that's being done to the car is raising the ride height. I might be able to accommodate you.

Mark, thanks for that. I’ll PM you tomorrow to see if we can arrange something.

I missed that. And if lowered significantly, I believe you.

Thanks for chiming in, Bill. I’d have no problem going to 205/50 on the front but for that if I do get a new set of wheels they’re already coming with brand new tires on them, and my current front tires still have plenty of life on them. It’s something I’ve wanted to do, but not if it costs a pile. to be honest, I just like the way they look, though I appreciate the merits of low unsprung weight enough that I don’t want to put a really heavy setup on it (I’ve tried to find a typical complete wheel and tire weight for a stock 16x6 and 16x7 on 205/55 and 225/50 but haven’t found it yet). I don’t recall if the scrub radius changes any with the wider tire. I’d rather not do anything to increase steering effort (eg more negative camber) if I don’t have to, and would be more inclined to just raise the front end. I have only ever driven my 911 since I got it until I drove a friend’s 930 the other weekend, and aside from being an absolute riot with the power delivery, I was struck by how much lower the steering effort was. I can live with the bump steer that comes with my ride height but turn-in isn’t the greatest compared to that car.

Older Fuchs 7x16 weigh ~14#+/- newer versions seem to be somewhat lighter

Here's a comparison of 2 different 7&8x16 Fuchs setups on an SC/Carrera, I arbitrarily choose A052 because the are available in all the sizes chosen here.

I much prefer setup #1 on the left as it moves ~26lb-ft from spinning up the wheels to accelerating the car and the lower profiles of the tires will generate more mechanical grip.
http://forums.pelicanparts.com/uploa...1718290783.jpg


scrub radius does change when going from Fuchs 6 to 7

w/ 7s it is a large 52.4mm
w/ 6 it is 65.1mm

both of these are large by modern standards, most cars now run 0 to -6mm for s/r

Bill,

Yes, I know most cars have much lower scrub radius than they did decades ago. I'm assuming it was substantially lower on the original 911 with its skinny little tires, too, if still positive. I'm surprised scrub radius is slightly lower on the 7s than the 6s - I would have supposed the opposite. So that change would suit me. I would imagine that changes in SR from more camber or from a smaller diameter are trivial.

If I do put them on my car it's going to be a package ready to just bolt on with the stock 16" sizes.

I appreciate all your suspension and tire input over the years.

Otter,
PM sent

Otter: The reason the SR is less on the 7's than the 6's is a combination of different offset and wheel width. The edge of the 6's sits as close to the fender as the edge of the 7's. Since the 7's are wider, they are wider to the inside of the wheel well. Thus the centerline of the 7's is closer to the centerline of the car by 1/2", and the SR is 1/2" less.

Per Bill V, the SR of the 6's is 12.7mm more than the SR of the 7's. 12.7mm is 1/2".

BTW, because the 7's are wider to the inside, it's common for 16x7 tires to rub the inside of the wheel wheel, rather than the fender.

My RS clone (1970) runs 944 Turbo 7s up front with 9s in the rear. I also rolled the front lips, Louisville slugger style.

I said I did the math a while ago, and I did, but it was so long ago that I apparently conflated my takeaway with that on my Fiat. I got some Biturbo wheels to put on it that are an inch wider and that increase is split between in and out. I didn’t really realize until Bill’s comment that all the extra went inside on the 7s. Another commenter who is local shared photos with me of wheel rub witness marks on the inner fender of his car. I’ve found a local set that I can swap onto the car to test and I’m going to see how they fit on Sunday.

PeteKz and Otter74 -- interesting! Still trying to figure out why the outer (not inner) edge of my right front tire shredded on (and pulled out) my right front fender lip when I switched from 16x6 fronts to 16x7 fronts (without otherwise changing alignment/etc.). Rolling my front fender lips resolved this for me.

here's a detailed comparison of a Fuch 6 and a Fuch 7, the 944 7 is the same except that it has increased caliper clearance, both have the same 205/50 x16 tire mounted
http://forums.pelicanparts.com/uploa...1718474827.jpg

both 6 & 7 have the same backspace the extra inch is all on the front space.

the scrub radius is solely dependent on the wheel o/s aka ET the 6 has ET38 the 7ET23.3, the difference in ET is 12.7 w' the 7's centerline closer to the hub face.

Otter, I’m in Chicago and run 7s up front on Yoko A052s (I think). I ended up having to roll the inner fenders as I bottomed out a couple of times. Probably a hair too tight.

You’re more than welcome to come check them and think we’ve exchange deets in the past.

So now I’m curious how, given that the extra inch is all on the back side, some people have gotten rubbing on the fender lips with 7s but not 6s.

I’ll find out tomorrow what happens on my car.

Yes, we have, and thank you. I’ve had two offers both in the north suburbs and hope to find out how the fit is after the show on Sunday morning. I’ll let you know if I want to try yours. I appreciate all the help.

I’d like to thank those that offered help. I went by @HLcass’s house today, swapped on the front wheels from his car and went for a drive. No clearance issues at all. I appreciate it!

good to hear

but the extra inch is all on the front side

It's because the extra inch in all on the outside

only time ever see w=ear on the inner chassis wall is when 8ET30 is installed w/ 245 tires

I have 8ET25 on mine and have used 225 and 235 tires, The car is very low. top of the fenders is the same height as my 993 which is at 993RSR height(704mm to the top of the fender) no rub on the inside.

I spoke to @GG Allin today and he showed me photos of the car in question and I suspect that the front wheels on that car are 944 7’s.

Still, when I put ET 23.3 7s from a Turbo on mine, it was fine despite the lowering. The wheels I’m considering are replaicas but same offset.

all 7" Fuchs whether 911 or 944 have the same o/s or ET, 23.3mm
all have the same lip width
doesn't matter if they are 15 or 16, 911 or 944 part #s

the only difference w/ the 944 versions is increased brake caliper clearance and countersunk lugs on the 944 versions

Replicas may or may not have the same 23.3mm ET and probably don't have the narrow lip spec that all Fuchs have. All Fuchs have ~.35" lips almost all modern wheel have .5"

The most different versions of Fuchs can be seen in the 6's and a very rare 7r

early 6 have 42mm deep valley at the petal ends and late have 20mm deep valleys

early are tube type w/o the safety humps seen on tubeless
http://forums.pelicanparts.com/uploa...1718571421.jpg

This is a 7R ET49 no tubeless safety hump

http://forums.pelicanparts.com/uploa...1718571518.jpg

deep 6 on left '72 on 6 w/ tybeless safty hump

http://forums.pelicanparts.com/uploa...1718571548.jpg

6 w/o hump
http://forums.pelicanparts.com/uploa...1718571605.jpg

7 944 part # w/ recessed lugs and larger caliper clearance on right 911 7 on left

http://forums.pelicanparts.com/uploa...1718571718.jpg
http://forums.pelicanparts.com/uploa...1718571718.jpg

Thanks for the correction on the 944 7s, Bill. I’m not sure why the tires on that car are rubbing (I haven’t seen it, but the wheels looked like 6s in the photo)

My ideal wheels would be a set of 7/8x16 Group 4 Campagnolo replicas, but none of those available not within my budget :)

Bill V is usually right about this stuff (and schools me), but I could swear that the 16x6's sit almost as close to the fender as the 16x7's. I wish I had a 16x6 laying around so I could compare them side by side. I do have a pair of 15x6 and a pair of 15x7, so I could check the ETs and compare those...

15s and 16s have the same dimensions except for the early versions I mentioned above
Here are the specs for most Fuchs used on 911
http://forums.pelicanparts.com/uploa...1718725115.jpg

and the fitment envelopes
http://forums.pelicanparts.com/uploa...1718725115.gif

I'm following this thread because I want 8 x 16 for the rear of my SC. May move the 7's to the front. Bill, it seems I can buy 911 or 944 8" for the rear, either will work, correct? Thanks

You can certainly buy them but the 944 8 has the wrong ET for either end of a 911

They are ET23.3 and almost fit the front, some have used them there but the cost is higher ride height and more aggressive camber setting
for the back of an SC/Carrera you will want 8s to have ET10.6 ore a little higher like ET 8 or so. The lower the numerical ET the more the tire sticks out and the less lip room.

you will want 7ET23.3 front and 8ET 10.6 rear

tires could be 205/55 or 205/50 front and 225/50 rear
or for better performance 205/550 and 225/45

Thanks Bill. I got the 7" discussion mixed into my 8" question....sleep will help me.

Lowered with 7&8 16s
 

My car came lowered from the PO with 6&7 16s, 20mm spacers and 205/55 225/50 tires.
I checked the fenders were already rolled a bit so I switched to 7&8 16s, kept the tires and ditched the spacers.
No rubbing or contact issues with the new setup.
http://forums.pelicanparts.com/uploa...1718897166.jpg

Thought I'd update this thread - bought a set of 7s and 8s, they're on the car, all is great.

Found last weekend that I do get some rubbing on the left rear under hard cornering with bumps:

http://forums.pelicanparts.com/uploa...1729194648.jpg

Doesn’t bother me - including this for future reference.

something is amiss

In the back of an SC/Carrera 225/50 x16 on 8 ET10.6 will have plenty of room at any ride height

Check your camber. That will affect clearance too.

Will look up alignment settings. Car was aligned and corner balanced a while back, and no reason to expect the rear to have changed. With the characteristic asymmetry these cars often has, my left rear is about 1/2” closer to the fender than the right rear. Will check when I put car on stands and remove wheels to do maintenance, but IIRC these are ET10.6. Rubbing is roughly where that smudge happens to be, on the back side.

While there can be some asymmetry 1/2" is a lot and beyond the norm.

How did you determine the 1/2"?