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

[Otter74]

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!

[Bill Verburg]

Originally Posted by Otter74

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 .

[PeteKz]

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.

[Bill Verburg]

Originally Posted by PeteKz

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

it's lowered quite a bit.

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

[Otter74]

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.

[Otter74]

Photo for ride height reference

[GG Allin]

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.

[Otter74]

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

[PeteKz]

Originally Posted by Bill Verburg

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

[Otter74]

Originally Posted by Bill Verburg

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 .

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.

[Bill Verburg]

Originally Posted by Otter74

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 it (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.



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

[Otter74]

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.

[Hlcass]

Otter,
PM sent

[PeteKz]

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.

[Billiam 911 2.8]

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

[Otter74]

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.

Originally Posted by PeteKz

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.

[darrin]

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.

[Bill Verburg]

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


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.

[Glenfield]

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.

[Otter74]

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.