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More 16/17 Fuchs wheel questions. Last steps and thoughts.

Trying to figure out a good wheel combo has been driving me crazy. Between trying to fill out the flare, keep down unsprung weight, not get tire rub, lose the spacers, etc. I posted another thread that was very helpful and I've been in contact with Braid about a set of rear wheels. I'm gonna fly this by you guys to make sure this all works, I will also include some of my discoveries (and eventually results) so these posts can be helpful to others.

Car: Stock 911sc
Body: Turbo flares
Wheels (current): 16x7 Front 16x8 Rear (stock)

Goal: Better fill out arches, especially rear. Don't lose too much acceleration hopefully improve handling and create space for future brake/suspension upgraded.

Issues: Very limited tire options on anything wider that 8" on 16" wheel. Daily driver so i can't run slicks. 17" wheel provides better tire options but that leads to more unsprung weight, drag, slower acceleration, etc. Can't copy a 930 setup because the suspension is different and the wheels won't fill exactly the same.

Potential solution:

Step 1. Move the 16x8's to the front (someone please confirm they will fit, I've heard they don't with stock sc flares, hoping they do with turbo flares).This fills out front arch.

Step 2. But 17x10 Braid wheels for the rear. Braid rep suggested a -33 offset. Sounded deep to me at first until I saw the spacers on my car are huge and I'm still not filling out the arch. I hear turbos can be -28 with 10" wheels maybe the extra -5 mm is to compemsate for SC suspension? (Again if someone can confirm this would fit that would be great)

And here's what I've discovered:

Matching tires can be a pain with different sizes, especially smaller 16 inch wheels. But I found these: Continental ExtremeContactSport that are available for both 17x10 and 16x8 inch wheels.

17x10 285/40/17
16x8 225/50/16

These are GREAT tires if you live in warm climates, the biggest negative is that they will cost $850 per change vs $550 which i payed previously. Definitely better quality, stickier, etc than my current tires though (Kuhmo Ecsta).

Now to specs... I actually don't lose that much if my math checks out right:

Current rear: Kuhmo Ecsta 245/50/16 27lbs, 25.7" tall, 808 revolutions per mile

Goal rear: Continental ECS 285/40/17 26lbs, 26" tall, 799 revolutions per mile.

The wider wheels actually weigh a pound LESS and are barely taller to boot. Assuming the 10inch braids weigh 3 pounds more than the 8 inch Fuchs I'll only be adding 2 pounds per rear wheel after the 1lb loss from the wheel.

Current front: Kuhmo Ecsta 225/50/16 22 lbs, 24.9" tall, 834 revolutions per mile

Goal rear: Continental ECS 225/50/16 22 lbs, 24.9" tall, 834 revolutions per mile

Exact same specs for front wheels. The 8 inch Fuchs weight maybe 1-1.5lbs more than the 7's.

All in all i should be adding (absolute max) 10 pounds to the car. They say unsprung weight gets multiplied by 10 so we'll say 100 effective pounds. But i get a much more filled out fender, better tire options which should allow better grip, handling, breaking, and some future proofing since our 16" wheel options do nothing but decrease over the years.

Thoughts? Pics not working will try to post in comments
Old 07-10-2019, 10:54 AM
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Pics of spacer and wheel fitment. The fitment looks worse when looking straight on or from right behind the car but I dont currently have a picture on hand.
Old 07-10-2019, 10:56 AM
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Quote:
Originally Posted by nkotselas View Post

All in all i should be adding (absolute max) 10 pounds to the car.
Did you include the extra weight from the larger tires?
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Old 07-10-2019, 11:38 AM
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Originally Posted by Driven97 View Post
Did you include the extra weight from the larger tires?
Yes I should have been more clear by listing it as "tires" but where I have the "current front goal front" is where I start the tire comparison. The front tires weigh the same and the rear tires actually drop by one pound, I assume because a better quality (higher tech) tire and also less geared towards all weather driving which i just assume adds some weight in rubber.
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Old 07-10-2019, 12:40 PM
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You'll have multiple issues
1)6x16ET10.6 don't fit the front, they will stick out ~ .5: too far
2) 10x17 rears don't fit either w/ ET-33 they will stick out ~2.5" too far
3) while weight id important tire OD is far more important The 245/50 x16 that you already have are too da** tall the 285/40x17 are much worse




Here's a pretty much maxed out 17" fitment. This is my car and the only reason it still has 225/255 x17 is the hot rodded 993 motor in it. For a stockish 3 liter I'd probably use 7 & 9 215/45 & 245/40 x17


This is what it looks like
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Old 07-10-2019, 01:40 PM
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Quote:
Originally Posted by Bill Verburg View Post
You'll have multiple issues
1)6x16ET10.6 don't fit the front, they will stick out ~ .5: too far
2) 10x17 rears don't fit either w/ ET-33 they will stick out ~2.5" too far
3) while weight id important tire OD is far more important The 245/50 x16 that you already have are too da** tall the 285/40x17 are much worse




Here's a pretty much maxed out 17" fitment. This is my car and the only reason it still has 225/255 x17 is the hot rodded 993 motor in it. For a stockish 3 liter I'd probably use 7 & 9 215/45 & 245/40 x17


This is what it looks like
Thanks Bill but is the above true even with the turbo flares. I've got so much space under there I don't know what to do with.
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Old 07-10-2019, 05:10 PM
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Quote:
Originally Posted by nkotselas View Post
Thanks Bill but is the above true even with the turbo flares. I've got so much space under there I don't know what to do with.
My bad, I missed the 930 flares

the wheels may fit but the other issues are still relevant, w/o a lot of motor you want to keep the tire OD down to ~25" or less keeping weight down is a secondary consideration.

additionally keep in mind mass near the axis of rotation in far more benign than mass further away. The effect of the wheel spacer mass is negligible the effect of the rubber at the tire perimeter is not
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Old 07-10-2019, 06:54 PM
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Quote:
Originally Posted by Bill Verburg View Post
My bad, I missed the 930 flares

the wheels may fit but the other issues are still relevant, w/o a lot of motor you want to keep the tire OD down to ~25" or less keeping weight down is a secondary consideration.

additionally keep in mind mass near the axis of rotation in far more benign than mass further away. The effect of the wheel spacer mass is negligible the effect of the rubber at the tire perimeter is not
Yeah the rotational mass surely will be an issue.

My problem is I don't think i have any other solution do i? The widest tire I can find for a 16 is a 255/50 (which is also taller), everything bigger than that are racing slicks. With 245s now I can tell 255s won't fill out the wheel well. And my spacers (at least i think they are spacers) are already huge and can't be much bigger can they? I feel like my only option is 17 rears. I'd hate to adversely affect performance but I'd hope the euro compression 3.2 can at least keep it to a minimum, it's no turbo though that's for sure.
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Old 07-10-2019, 09:33 PM
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Sorry if you already know this, but stock 930 tire sizing was 245/45/16 in the rear, on 9" wheels. (And 205/50/16 in front, on 7" wheels.) So not sure why you don't believe the 255s will fill out the wheel well. OK, maybe there's lots more room to go (the widest tire 930s can run are 315s in back--actually, maybe even 335s, but no one makes a tire in that width/aspect ratio that fits), but 255s won't look totally emasculating. Is it just the wheel offset that needs to be tweaked to make the wheels sit further outboard to make the stance (gawd I hate that word) better? (I take it Braid doesn't offer that level of customization?)

If weight is a huge concern, the Fikse wheels I'm running are fairly light. My bathroom scale says the 17x11 rears are only something like 18 or 19 lbs. Custom sizing, with their 3-piece design. You can figure out whatever offset, width, and backspacing you want. And you'll like get sexy deep dish with your wheels. But the negatives include their $$$$ price and super slow order times. And if you actually break a wheel, it takes a fair bit of patience to get replacement parts.
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Old 07-10-2019, 10:28 PM
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Quote:
Originally Posted by Noah930 View Post
Sorry if you already know this, but stock 930 tire sizing was 245/45/16 in the rear, on 9" wheels. (And 205/50/16 in front, on 7" wheels.) So not sure why you don't believe the 255s will fill out the wheel well. OK, maybe there's lots more room to go (the widest tire 930s can run are 315s in back--actually, maybe even 335s, but no one makes a tire in that width/aspect ratio that fits), but 255s won't look totally emasculating. Is it just the wheel offset that needs to be tweaked to make the wheels sit further outboard to make the stance (gawd I hate that word) better? (I take it Braid doesn't offer that level of customization?)

If weight is a huge concern, the Fikse wheels I'm running are fairly light. My bathroom scale says the 17x11 rears are only something like 18 or 19 lbs. Custom sizing, with their 3-piece design. You can figure out whatever offset, width, and backspacing you want. And you'll like get sexy deep dish with your wheels. But the negatives include their $$$$ price and super slow order times. And if you actually break a wheel, it takes a fair bit of patience to get replacement parts.
Thanks for the input.

I think part of the issue is the difference in the SC and turbo suspension. The cars apparently don't sit the same and the wheels in the 930 do fill out more because of it. That being said it did totally akip my mind that i can just get a more negative offset set of 16's for the rear. I'll have to pull the ones on now and check. Maybe going 16x9 or 10 just with a deep offset is the ideal solution? Is there a specific offset you recommend?
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Old 07-11-2019, 05:31 AM
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Feels to me your over tiring the car with the current suspension and motor. What your going to get is a sluggish steering and acceleration. Your not going to get much, if any improvement in handling or braking just with fatter tires.
As far as tire fit the 255's on 8 or 9's front and up to a 315 on 11x17's will work.

On our '75 Carrera race car with turbo fenders and 911 trailing arms we ran 245/45/16 fronts and either 295 or 315/17 rears. 2.5 front camber, 3.0 rear camber. We had a fairly taut suspension set so tire rub wasn't an issue. I also fit 270/15 Michelin TB's on 9" rims on the front which cleared but the tires were too tall. I've also seen guys fit 275's on the front. In the shot below I went back to 1.5 camber in the front and 2.0 rear.

On our '73 E street track car with RS rear fenders and stock 3.2 we ran 225/45/16 fronts and 275/16 rears (Hoosier race tires). I ran 245's on the front but didn't notice enough improvement over the 225's so I went back to the 225's. The only engine mods were a Steve Wong chip, SSI's and a sport muffler. We did swap out the stock 8:31 r&P for a 7:31 which had great improvement on the bottom end.

For the 11x17 wheels I like 6" backspacing which lets me add a spacer to adjust how the wheel sits in the wheel well.

Here's a shot of our old Carrera with 245/45/16's on 8x16 3 pc. fronts and 315/35/17's on 11x17 3 pc rears.
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Old 07-11-2019, 07:19 AM
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Quote:
Originally Posted by nkotselas View Post
Thanks for the input.

I think part of the issue is the difference in the SC and turbo suspension. The cars apparently don't sit the same and the wheels in the 930 do fill out more because of it. That being said it did totally akip my mind that i can just get a more negative offset set of 16's for the rear. I'll have to pull the ones on now and check. Maybe going 16x9 or 10 just with a deep offset is the ideal solution? Is there a specific offset you recommend?
The difference between a 911 w/ 930 flares and a true M491 car is the rear semi-trailing arms in back and the hubs up front. Both push the wheels of an M491 out more than on a regular 911. 930s also used spacers, thru '80.5 930 used a 21mm spacer in front for '80.5 up the hubs were changed so the spacer was no longer used. All 930 use a 28mm rear spacer.

stock wheel fitment for 930 varied over the years but 7ET23.3 & 8ET10.6 or 9ET15 x16 was the basic fitment.

what you want isn't going to be done cheaply unless you want to use spacers which I would avoid.

you will want custom ET wheels, filling the appearance of filling the wheel wells comes from having the final wheel/tire front space pushed out as far as it can go w/o interference w/ the fenders. This can be done w/ either 7& 8 or 9 Fuchs + spacers or by different wheel widths & different more aggressive ETs. You still want to keep tire OD under 25", lower the car if necessary to get the look you want.

in 15
use 8 & 9 w/ 225/45 & 245/40 tires, OD ~22.7"

in 16 use 8 & 9 w/ 225/50 & 245/45 tires, OD ~24.7"

in 17 use 8 & 9 w/ 215/45 & 245/40 tires, OD ~24.6"

in 18 use 8.5 & 10 w/ 225/40 & 285/30, OD~24.7"

you can use wider wheels and tires but you don't gain anything unless you are tracking the car and you lose acceleration and braking. The whole trick is to get the rights ET for the wheel width used.
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Old 07-11-2019, 09:21 AM
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Forgot to add that if you go to tall tires a cwp change can undo much of the damage but that has it's own costs(besides $)
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Old 07-11-2019, 09:24 AM
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Quote:
Originally Posted by Bill Verburg View Post
The difference between a 911 w/ 930 flares and a true M491 car is the rear semi-trailing arms in back and the hubs up front. Both push the wheels of an M491 out more than on a regular 911. 930s also used spacers, thru '80.5 930 used a 21mm spacer in front for '80.5 up the hubs were changed so the spacer was no longer used. All 930 use a 28mm rear spacer.

stock wheel fitment for 930 varied over the years but 7ET23.3 & 8ET10.6 or 9ET15 x16 was the basic fitment.

what you want isn't going to be done cheaply unless you want to use spacers which I would avoid.

you will want custom ET wheels, filling the appearance of filling the wheel wells comes from having the final wheel/tire front space pushed out as far as it can go w/o interference w/ the fenders. This can be done w/ either 7& 8 or 9 Fuchs + spacers or by different wheel widths & different more aggressive ETs. You still want to keep tire OD under 25", lower the car if necessary to get the look you want.

in 15
use 8 & 9 w/ 225/45 & 245/40 tires, OD ~22.7"

in 16 use 8 & 9 w/ 225/50 & 245/45 tires, OD ~24.7"

in 17 use 8 & 9 w/ 215/45 & 245/40 tires, OD ~24.6"

in 18 use 8.5 & 10 w/ 225/40 & 285/30, OD~24.7"

you can use wider wheels and tires but you don't gain anything unless you are tracking the car and you lose acceleration and braking. The whole trick is to get the rights ET for the wheel width used.
Thanks Bill, I had looked into it a bit after your previous post and also came to the conclusion of 225/50/16 and 245/45/16 and have already found matching tires in those sizes. I guess with the offset it doesn't matter much so long as it's negative enough to allow me to adjust with spacers to the right distance. I believe the braid rep told me et -33 for the rear does that sound to you like it would work? I really don't know much about wheel fitments and am hoping to buy these soon without any buyer's remorse.

If it matters he quoted me that on 17x10/11 wheels but now I'm leaning towards a set of 16x9 just wonderinf what offset, or range of offsets would work
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Old 07-11-2019, 11:44 AM
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Thanks gumba. That's a good look on that car.

I think after some discussion I'll stick with 16" wheels. Move the 8"s to the front buy 9"s for the back. Get lower profile tires lower the car a bit, and get spacers if necessary. Performance is why I enjoy driving the car and would rather not make it sluggish.
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Old 07-11-2019, 11:51 AM
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Quote:
Originally Posted by nkotselas View Post
Thanks Bill, I had looked into it a bit after your previous post and also came to the conclusion of 225/50/16 and 245/45/16 and have already found matching tires in those sizes. I guess with the offset it doesn't matter much so long as it's negative enough to allow me to adjust with spacers to the right distance. I believe the braid rep told me et -33 for the rear does that sound to you like it would work? I really don't know much about wheel fitments and am hoping to buy these soon without any buyer's remorse.

If it matters he quoted me that on 17x10/11 wheels but now I'm leaning towards a set of 16x9 just wonderinf what offset, or range of offsets would work
The problem is that when flares are added the results aren't all the same

I have data on multiple wheel-sets for your application
for an 11 the ET's I have on file range from -8 to -31 this gives a front space of from 6.2" to 7.1" the tires on the rims spill over a bit but not enough to account for the wide range of data.

Best is for you to determine what you have and then measure careful how much further out you want the wheel lip to be.. You'll need to know the present wheel width and ET and the spacer thickness, tire data would be helpful too.

just as a FYI one of the wheel sets I have on file is Braid 9ET-17 & 11ET-25 x17 w/ 255/40 & 315/35 tires
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Old 07-11-2019, 12:47 PM
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Quote:
Originally Posted by nkotselas View Post
Thanks for the input.

I think part of the issue is the difference in the SC and turbo suspension. The cars apparently don't sit the same and the wheels in the 930 do fill out more because of it. That being said it did totally akip my mind that i can just get a more negative offset set of 16's for the rear. I'll have to pull the ones on now and check. Maybe going 16x9 or 10 just with a deep offset is the ideal solution? Is there a specific offset you recommend?
I don't have enough experience to give any detailed advice. I have a 930, and I realize you have SC suspension with turbo flares. I know they're different, but I apologize that I don't know enough to give you any worthwhile numbers. Of course, if our paths cross, you're welcome to test fit my wheels on your car to see what doesn't work.
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Old 07-11-2019, 10:30 PM
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