Michael Robertson

Hey Guys...

I know this is a topic that has been revisited countless times by some of the more seasoned guys, but I can't just seem to find the info that I need to make my purchase easier.

To put it simply - I have an 88 944 Turbo S with m030 suspension and I want to put 17 inch wheels on it.

I would appreciate it if somebody could supply me with the correct sizing, offsets and all other information I would need for 17 inch wheels that will just 'bolt on' to my car without the need for spacers etc.

I'd like to put wheels from a newer porsche and any wheels that would just bolt on would be greatly appreciated.

Thanks,

Michael

IceShark

You want something close to 65mm front and 60mm rear offsets, depending on how wide of tires you are trying to run and if you want some sort of flush look, like Robby.

How wide for the rims again depends on how wide you want to run the tires. I think some have run nearly 315mm in the rear. I run 275mm in rear and they fit no sweat, and my rear wheels are only a 52mm offset.

So first decide how fat you want to go on rubber.

Robby

I ordered some .125" spacers for mine- they were $30 for a set of 4, including postage- from another Rennlist poster. I'm only planning to use them on the rear. I know that 1/8" isn't much, but I'm hoping not to have to run longer bolts, or different lug nuts, and I understand that 1/4" is about as far as the stock one's can be pushed- I like my titanium or aluminum (depending on who you ask) lug nuts I'm hoping the 1/8" will push the rears out just enough to make a slightly noticeable difference...

Danno

Yeah, IceShark's right on with the stock offsets (65/60m). However, there aren't ANY stock 17" Porsche wheels that carry these offsets. If you go with 52.3mm offset wheels, then you would need to go down to a narrower 7" wheel with 205mm tire to prevent rubbing on the front fender.

So means your choices are really 3-piece aftermarket wheels. Here are some links:

My favorites has got to be the Simmons OM wheels:

Since they're Aussie wheels, you can probably find local distributors for better pricing than from the U.S. with shipping.

Any way you go, I recommend a set of 17x9 (70mm offset) front and 17x10 (65mm offset) rear. This will place the outside edge about 5mm outward from your stock wheels with most of the extra width on the inside. Then you can use 255/275mm tires or even 275/315mm if you roll the fenders.

Here's the official Porsche statement on 17" wheels on 944/951s (ignore spacer info):

----------------------------
ARTICLE BEGINNING

TECHNICAL SERVICE BULLETIN : 17 INCH APPROVED WHEELS & TIRES

Model(s):
1987-On Porsche 944 (with M30 option) 1987-On Porsche 944S (with M30 option)
1987-On Porsche 944 T (with M30 option)
1988 Porsche 944 Turbo S
1989 Porsche 944 Turbo
1989-On Porsche 944 S2

Group: 4
Bulletin No.: 9303

Date: September 28, 1993

SERVICE INFORMATION

Concern: Installing 17" Porsche wheels on vehicles previously equipped with 16" wheels.

SERVICE PROCEDURE

Installation Information

1. Front and rear fender well lips must be reworked and/or checked for adequate tire clearance. See Fig. 1.

2. Suspension travel must also be checked. Parts such as brake lines, hoses and brackets must have adequate clearance.

3. New caster eccentrics, rear mounts and nuts must be installed in the front control arms. This change is necessary due to a change in caster specification on vehicles equipped with Porsche 17" wheels. The specification for vehicles equipped with 17" wheels is 3'-15'-45. See Fig. 2.

4. Vehicles must have a rear stabilizer bar.

5. When adjusting vehicles to new caster specification, all alignment values should be checked at that time.

6. When summer tires are used on vehicles with 17" Porsche wheels, snow chains cannot be used. If winter tires are used, only snow chains with Porsche Part Number 911 361 924 00 may be used.

7. Tire pressures for front and rear 17" Porsche wheels is to be set at 2.5 bar (36 PSI) at approximately 20'C (68'F).

8. When using this rim and tire combination, a 17mm spacer plate must be installed on the rear wheel hub. The customer must be informed that if the emergency wheel is needed, the spacer must be removed.

9. Not for Cabriolet vehicles.

APPROVED WHEEL & TIRE TABLE

Tire size Rim size Offset Position Note

225/45 ZR 17 7,t Jxl7 AH 65mm Front Summer tires
255/40 ZR 17 9 Jxl7 AH 55mm Rear (See installation information A through G.)
225/45 ZR 17 8 Jxl7 AH 52mm Front Summer tires
255/40 ZR 17 94.@ JX17 AH 68nm Rear (See installation information A through I.)
205/50 R 17 7;-i Jxl7 AH 65mm Front Winter tires
225/45 R 17 8 Jxl7 AH 52mm Rear (See installation information A through G.)

NOTE: When using this rim and tire combination, a 17mm spacer plate must be installed on the rear wheel hub. The customer must be informed that if the emergency wheel is needed, the spacer must be removed.


PARTS INFORMATION TABLE

Description Part Number Quantity

Spacer Ring 951 331 611 02 2
Wheel Bolt 904 341 671 00 10
Wheel Nut 999 1 82 003 36 10


APPROVED WHEEL PART NUMBER TABLE

Size Offset Part Number

7;-i Jxl7 AH 65mm 96536212405
8 Jxl7 AH 52mm 96536212601
9 Jxl7 AH 55mm 96536212800
91.@ Jxl7 AH 68mm 96536212805


APPROVED TIRES AND SIZES (SUMMER VERSIONS) TABLE

Size Makes

225/45 ZR 17 Front Bridgestone Expedia S-01 Nl
255/40 ZR 17 Rear Continental Sport Contact CZ 91 NO
Pirelli P700-Z NO
Yokohama A 008P NO
Michelin MXX 3 NO or MXX NO Pilot SX


APPROVED TIRES AND SIZES (WINTER VERSIONS) TABLE

Size Makes

205/50 R 17 89 H M&S Front Bridgestone WT05
225/45 R 17 90 H M&S Rear Continental TS 750
Pirelli winter 210 Performance


SUSPENSION PART NUMBER TABLE

Suspension Parts

1. Rear Mount

Part Number Quantity Required
951 341 023 00 2 each

2. Eccentric 951 341 431 02 2 each

3. Nut (torque to 100 Nm) 900 910 115 02 4 each

END OF ARTICLE
------------------------------

ste

Thanks for reproducing that Danno. I needed that info.

Cheers

ed devinney

Single data points don't make for good conclusions, but I've been running 993 cup rims on my lowered S with no problems. 17x7 and 17x9 with 225/45 fronts and 255/40 rears. Have run a bunch of street miles and one track day last week - semi-pro driver friend took it out to demo to a customer, too. If he didn't find a problem, they should do well for my purposes. The rolled fender lips of the S do seem to help.

Danno's tech note reminds me I should have the alignment checked this winter if I'm going to run these more.

Jerry

I can't understand why I had no problems with my 17" 993 wheels I purchased used at $1K for my track tires for my 88 944ts. They fit perfect in every way and I can put 275's all around if I wanted. I think they are the best looking, they are light weight, and they are Porsche.

Danno

Ah, you're most welcome!

Hmm, going to non-S rims of the same width will have the front wheel sit 1/2" outwards and the rear 1/3" further out. So yes, they can be used. But you're limited to 7.5/9" widths which is fine since the Porsche 17" wheels appear most popular in that size.

I'm really talking about optimizing offsets to get maximum rim-widths and tires under the fenders for maximum performance like GT-style racing. I've got a set of 17x11/12" BBS racing wheels coming and the trick to getting them to fit is to put most of the extra width on the inside where there's more room (increase offset).

nsxcar

Hey Danno,

Resurrecting an old thread, but seen your posts in quite a few different forums regarding 951 wheel sizes and offsets.

Wanted your thoughts on the bulletin you and so many have posted.

In another thread you said that as width increases the offset needs to increase and that is why as the 951 wheel size increased so did the offset. Now I am wondering as I am about to buy some 17 for my 89 Turbo, how come the Porsche bulletin has front 17x7 et 65 but front 17x8 et 52? Sounds strange that they would add an inch and then push it out an additional 13mm. Would this even fit under the fender?

I am currently looking at 17x7.5 et 65 and 17x9 et 55, but these can be custom built so I was trying to figure out if I went with 17x7.5 or 17x8 what right offset would be to keep the wheels aesthetically pleasing but still under the fender. This is just a weekend car so no track time or else I would use those ultra wide setups that you have recommended.

Your insight would be much appreciated.

944Fest (aka Dan P)

Danno hasn't been here in 19 years.

nsxcar

Oh, hopefully he is ok. But he seemed like the expert on wheels and offset.

maybe some else bumps into this and can confirm if 8x17 et 55 will work on a 1988 Turbo S front without issue. Seems like so many mixed answers out here.

Thanks!

JustinL

Yes they will fit.

nsxcar

@JustinL

Is your answer from first hand experience?

Would you change the offset, assuming that you didn’t need or want wider tires? This would be more cosmetic to make the wheels pushed out but still under the fender.

Is 9.5x17 et 55 too conservative for the rear?

For tires I would likely run 235/45 front and 255/40 rear.

Thoughts?

Thanks in advance.

JustinL

You can run a clubsport rear on the front, which sticks out more and has less inside clearance. You can pop one of your rear wheels onto the front to get a feel for the fit. Use the 1010tires offset calculator to get an idea where your prospective wheels will line up.
I must admit that I haven't had stock springs for a long time, so I have more flexibility with wheels. But I've also tried a lot of combinations including 10" ET55 fronts that can be made to fit with the right springs and camber plates. I think my current wheels are very close to what you are hoping to run. I don't have the exact measurements, but I think they are close. I run a bigger set of tires with 255 front and 275 rear. Your planned tires will have a bit of stretch to the sidewall, where as mine have a bit of bulge. Mine is the silver car and I have quite a bit of camber as it spends a lot of time at the track (when it's not on stands though).