Wheel Options: 15x8R? Does it exist?

[jpnovak]

I did a search... Could not find anything. Please post a link if you have a solution.

So... I made conscience decision to retain stock rear flares on my 72 project. This limits my wheel choice to a typical 15x7 rear application and "maybe" a 225 rear tire. The car will be light and this should be enough. But... I would like to consider something different.

Has anyone made a 15x8R offset wheel? for reference here is what we have to work with.

911R 15x7 (48mm offset 138mm backspace)
15x6 (36mm offset, 112mm backspace)
15x7 (23.3mm offset, 112mm backspace)

The 15x7 911R wheel is offset to the inside wheel well compared to a 15x6. The standard 15x7 is offset to the outside compared to the 15x6.

I am wondering about a 15x8 with a 138mm backspace. I think it would fit under the rear or a narrow body 911. Similar to the 951 16x8 (125mm backspace) but more.

Appreciate any thoughts you guys have. Can 15x7 be cut and welded with an inch of Aluminum in between? Any sources for this?

Yes, I know tire choice will be slim. Let's solve the wheel availability first.

[Bill Verburg]

Originally Posted by jpnovak

I did a search... Could not find anything. Please post a link if you have a solution.

So... I made conscience decision to retain stock rear flares on my 72 project. This limits my wheel choice to a typical 15x7 rear application and "maybe" a 225 rear tire. The car will be light and this should be enough. But... I would like to consider something different.

Has anyone made a 15x8R offset wheel? for reference here is what we have to work with.

911R 15x7 (48mm offset 138mm backspace)
15x6 (36mm offset, 112mm backspace)
15x7 (23.3mm offset, 112mm backspace)

The 15x7 911R wheel is offset to the inside wheel well compared to a 15x6. The standard 15x7 is offset to the outside compared to the 15x6.

I am wondering about a 15x8 with a 138mm backspace. I think it would fit under the rear or a narrow body 911. Similar to the 951 16x8 (125mm backspace) but more.

Appreciate any thoughts you guys have. Can 15x7 be cut and welded with an inch of Aluminum in between? Any sources for this?

Yes, I know tire choice will be slim. Let's solve the wheel availability first.

Maximum backspace on a 911 is ~6"(152.4mm)
Maximum frontspace w/ sub SC rear flare is ~3.5"(89mm)

So any wheel within that envelope works OK but still depends on the tire width and height
a Fuch 8ET38(if it existed) has a f/s of 2.9"(72.5mm) and b/s of 5.8"(148.5mm)

change that to 8ET30 and f/s goes to 3.2"(80.5mm) b/s 5.5"(140.5mm)

The widest theoretical for a n/b is 8.5ET33 w/ f/s 3.3"(83.8mm) b/s 5.9"(149.8mm)

a 9 ca not be made to fit w/i the existing n/b envelope

[Mixed76]

Bill, what's the max front side for a pre-sc narrow body? 1.5"? Is the backside still 6"?

Dan

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[Bill Verburg]

Originally Posted by Mixed76

Bill, what's the max front side for a pre-sc narrow body? 1.5"? Is the backside still 6"?

Dan

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The above is the data set for pre SC

For all of them
front:
SC: max f/s 3.5, b/s 5.75 in.
88.9 146.05 mm
n/b; same
rear:
SC: max f/s 4.5, b/s 6 in.
114.3 152.4 mm
n/b: max f/s 3.5", b/s 6"
89 152 mm

[Mixed76]

Thanks Bill!

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[KTL]

driven97 (Matt) had a pair of Euromeister Fuchs replicas cut and welded to his specs. PM him and I suspect he'd be happy to share who he used to do it. He's in Michigan.

[jpnovak]

Thanks Kevin.

I was wondering about cutting Euromeister or Maxilites. Maybe even a pair or factory 15x7s.

I guess I need to measure some clearances.

[FrenchToast]

I would avoid welding wheels.

No, a 15x8 in "R" offset does not exist. Do you need tires that wide? Have you checked availability of tires for a 15x8 wheel? Does such a wheel and tire even fit in the well?

Originally Posted by jpnovak

I am wondering about a 15x8 with a 138mm backspace. I think it would fit under the rear or a narrow body 911.

By keeping the backspace the same as the R wheel, you're pushing the additional inch of width outboard.

Braid can probably make you a 15x8 in the custom offset you want.

[KTL]

I would disagree with the caution of welding wheels. Numerous OEM wheels are welded and used on road cars and they are plenty durable. The guy Matt I mentioned put his welded Euromeister wheels to the test very hard on autocross. Many people here have bought custom welded Fuchs wheels from Lindsay Racing and TruDesign (RIP Jim...) and they were very durable. Jack Olsen has been tracking his Lindsay wheels for like 15 years I believe.

[jpnovak]

I too disagree with welding wheels. I don't have any issue with them. I have had some Lindsey 17s welded Fuchs in the past and never had any issues. These wheels are now on their 3rd car and 16 years and no issues.

So... A 15x7 fits just fine. Consider this the outer side of the virtual 15x8R wheel. The extra inch is inboard.

I want to run a rear 245-40-15 tire. Section width is somewhere around 9.5 inches. I have 10.5 inches of clearance to the spring plate bolts. over 11 inches to the suction/supply oil line on my 72. Plenty of room to stuff more rubber under there.

Would run 225-45-15 on 15x7 up front.

Do I need it? That's debatable.

Do I want it? And do I want to push limits? That's why I ask these type of questions.

[Bill Verburg]

I don't know why I bother, apparently no one bothers to read

In back all 911 have ~6" max back space room, but at 6" the trailing arm bolts and oil line will need to be addressed


Here's a wheel w/ 6" b/s and a 275 tire, trailing arm nuts and bolt are shaved and the oil line relocated


A pre SC 911(non Carrera) has ~3.5" of front space, an SC/Carrera has ~4.5" of f/s, a 275 tire when perfectly placed barely fits in an SC/Carrera fender well on a 9.5.

The pre SC then can accommodate up to 9.5" tire(3.5+6) max this is 241mm, w/ additional lip work it might be possible to squeeze in a 245 but it'd be dicey and ride height restrictions are likely necessary as well as extra camber(which helps w/ the trailing arm but hurts wrt the oil line).


An 8.5 ET29-35 would just barely squeeze in to a n/b rear wheel well, closer to 29 puts the tie closer o the lip and closer o 35 puts it closer to the trailing arm/oil line

An 8 ET23.3-41 also squeezes in there again closer to 23 places the wheel closer to the lip and closer to 41 puts it closer to the trailing arm/oil line

Ingo runs 944 8ET23.3 225/50 x16 on his n/b 911, It is very tight at the lip

[kent olsen]

Hey Bill a lot of us read and appreciate your expertise so don't stop even when goofy questions come up.

I too have a 72 and tire clearances are an issue. Years ago, since I don't need to look like everyone else, I went to Australian superlite 15x7 wheels. Then the choice of tires was the next issue. So I have run, on my second set, Yoko Advan 205x50x15. They are a soft tire (180) but they last surprisingly long.

On a light car (2210lbs dry) with 9:1 power to weight (3.0L twin plug), the car is more than enough on the track or autoxing for an old guy like me.

[914/6]

https://weldcraftwheels.com/
Wiedman

[914/6]

rollin these 16x7.5 for 10 yrs..made from 16x6's .. one weld, used extra 16 rear halves from making 3pc centers..

[FrenchToast]

Originally Posted by KTL

Numerous OEM wheels are welded and used on road cars and they are plenty durable.

That may be, but a factory wheel is going to have a design reviewed by an engineer, have pieces placed in a bespoke jig, and be welded by a professional, certified welder in an ISO-certified facility.

I'm glad they work for some people. I personally wouldn't trust anyone other than a reputable wheel manufacturer to weld wheels, and I'd want design analysis, zero-hour components, known suppliers, certified welders, etc.

[KTL]

To each his own. Yes in a perfect world you can ask for the world. All i'm saying is the "field testing" has proven that welded wheels, from non-zero-hour components (as in, donor original Porsche Fuchs wheels for their center sections) have withstood the test of time. That said, nothing lasts forever and I too have felt that the cost involved, and the risk, to make a welded Fuchs wheel is high, considering the donor Fuchs wheels are often quite old. How much life do they have in them? Yet to be seen. However, I have seen numerous cracked Fuchs over the years. Those cracks typically reside at the center bore and connect to a lug hole.

Agreed a wheel provided by a vehicle manufacturer undergoes testing by the subcontracted manufacturer. The guys building these wheels aren't some dude in a garage who just figured out how to use the aluminum spool gun on his 110V Hobart hobby welder. They understand the risk and should use proper filler metal materials and setup to create a solid wheel. Of course they must set up the wheel in a fixture to ensure pieces are concentric and axially aligned. Poor set up resulting in misalignment/vibration will rear its head instantly and they can't afford that.

Also please don't discount the presence of a considerable wheel repair industry. They recondition and straighten/repair damaged wheels and put them back into circulation daily. Not saying that makes a repaired wheel good as new, ready for 24 Hours of LeMans. Just saying it's a sizeable industry with proven results.

I have no skin in the game here. I'm not pushing the welded wheels as a no-brainer. Just sharing my observations of owning a few sets of welded wheels:

Former '92 Plymouth Laser AWD Turbo (aka Mitsu Eclipse GSX) with OEM Eagle Talon wheels I bought for it. Turns out I realized they are factory welded two piece

Set of four Porsche Etoile/Gotti three piece welded wheels in my basement. Rim halves are welded together in the middle and the center is bolted to the rim halve flanges.

Along with my interaction with others who have the welded Porsche wheels and who have shared their history/use of the wheels