Duck

The PO put 18" TGF wheels on my 1990 C4 Cab. I have seen a few posts mentioning that Porsche did not recommend 18" wheels. What actual suspension concerns would there be and what should be inspected. I have no idea how long they have been on the car.

Since mine is a street only car, I will be switching back to 16 or 17" wheels when the current tires wear out. The current ride is extremely rough.

Thanks for the input.

Michael

993inNC

There is a steering rack brace that is recommended for 95 993's since they never came with 18's. I would guess the same applies for you too.
BTW, if you are new to the area or P-cars, our July PCA meeting is at McDaniel Farms restaurant this Sat from 9 am til. We just had our monthly Sunday "sporting" drive and are going to be working on future events. The local rep for the region also has a 964 cab.....may be someone to get to know
As well, we may be doing some extensive exhaust work on his car to free up about 40 ponies, might be something you are interested in.

cupcar86

Check with Adrian, don't forget the 964RS (Euro) came with 18" Speedlines as an option with Porsche part number and they are about as heavy as anything out there.

cupcar86

Sorry, heavy was in reference to the Speedlines. not the RS.

Duck

Hi Chris,

I have been wanting to attend the Saturday's at McDaniel Farms. Unfortunately my daughter's tennis lessons are at the same time. My wife plays league tennis as well and her practice is at that time. This Saturday is the last of my daughter's tennis lessons, so I am hoping to make the next meeting.

Thanks,
Michael

993inNC

see you then

Ritter v4.0

You mean free up more $$ from his wallet

993inNC

hey, hey, hey now.......gotta pay to play Yours is next anyway right?

964RS

Hi,

The 965 and the RS (Not the RS America) came with an other hub suited for a larger workload from heavy driving or a bigger wheel such as an 18" wheel. It is not recommended to fit 18" the weeker hub, even though many do.

Best regards
Anders
964RS and 18" Speedlines

Blu RS

Per CupCar 86
"the 964RS (Euro) came with 18" Speedlines as an option with Porsche part number"

It is well known that the 964 Cup car (from the 2nd year on) came with 18" Speedlines but I have never seen nor heard evidence that the Euro RS was offered with an option for 18" wheels. In fact the factory technical bulletin from that period restricted application of the 18" wheels from all narrow body 964 chassis except the Cup Cars, to include restricting their use on the Euro RS chassis. In 1992, as I was in Germany picking up my tourist delivery RS America, I wanted to buy the 18" wheels to put on my car, but Porsche Werks 1 refused to sell them to me. I discussed the matter extensively with the staff there at Werks 1 and was told that the factory had issues with using 18" wheels on both the front and the back. I was never told the specific problem in the front, but I was told the problem in the rear. The problem that concerned Porsche was regarding tire integrity with 18" wheels because the aluminum rim and tire bead on the left rear inside comes too close to the catalytic converter. Porsche feared that a tire bead or bead/rim failure could occur with a street car and months/years of heat cycles with 18" rims. Porsche was not concerned with the 18" wheels on a Cup Car because the tires were frequently replaced, if not the rims as well. Obviously quite a few owners of 964 chassis cars, including owners of some Euro RS chassis, have installed 18" wheels despite the factory's guidelines, but nonetheless the factory still has not approved the use of 18" wheels on the narrow body 964. And clearly there are numerous widebody 964 chassis with factory 18" wheels, which are permissible because there is greater clearance from the catalytic converter to the rim/tire juncture.

Per 964RS
"The 965 and the RS (Not the RS America) came with an other hub suited for a larger workload from heavy driving or a bigger wheel such as an 18" wheel."

The Euro RS came with alloy hubs in the front specifically for weight saving purposes versus the iron hubs on the series 964. The factory literature at the time did not make any mention of using the alloy hubs to achieve any purpose other than weight saving. You may infer that the alloy hubs are better for shedding heat versus the iron hubs, but Porsche did not say that. Of course the wheel bearings for the alloy hubs are exactly the same as the iron hubs, so it is not clear just how the alloy hubs would support a "larger workload . . . bigger wheel" better than the iron hubs, beyond the potentially greater heat shedding capability. By the way, I purchased and had these alloy hubs installed on my RS America years back and continue to use them, so I am quite familiar with these components.

Chris M.

Porsche issued a Technical Service Bulletin in 1993 stating installation of 18" wheels was not approved for 964s. It says that using them
"may result in loosened bolts and/or threaded connections on the front wheel carriers. This, in turn, may cause fractures in these components. Fractures may also occur in the front strut mounts and in the body in the area of the rear suspension as a result of the installation of 18" wheels not already approved for installation for this specific application. Such damage can occur without warning and the vehicle may become very hard to control or steer as a result of this improper installation."
Some people still use them so it's really up to you.

40 horses? Keep us posted.

Duck

Thanks for everyone's input. I will make sure I inspect the suspension closely. The quick look so far shows that I need new front drop links for the sway bar.

Again, thank you for the information.

Michael

cobalt

here we go again.

Although the speedlines are not light compared to some aftermarket wheels they are not heavy in comparison to other Porsche alloys used. The 8 X 18" speedlines weigh in at 25.39 pounds and the 10 x 18's weigh in at 26.75. In comparison 8 x 17 cup 1's weigh 22 pounds and 9.5 x 17" cup 1's weigh 27.5 pounds. The 18" BBS sport designs, GT3 and turbo look wheels all weigh more than the speedlines and only the 5 spoke Carrera BBS and hollow spoke technology wheels weigh less with the 993 hollows weighing in at 8" 19.58 and 10" at 23.32 the 996 hollows come in at 8" = 21.23 and 11" = 26.18

So as you see the speedlines get a bad rap and yes they are heavier but very solid and durable.

I have Fikse Pro V on my C2 in 8 and 9.5 and these are much lighter than any of the factory wheels and have no issues with them. Although they are harsh for street use and prefer the cup 1's instead.

Slantnose!

Actually, I trade off with the 18" Speedlines and stock 17" Cups.
No problems over here, althought the smaller wheels do feel smoother...