sml

Will the following wheels work ok on a 964 C4 ...

Porsche Sport Classic II 18"
REAR: FR-4400N RS-773 993-362 7VJ18-ET50
FRONT: FR-575RN RS-721 993-362 10J18 ET65

Computamedic

You've got the front and rears the wrong way around - 7J on the front, 10J on the rear. The rears will need 18mm spacers otherwise they'll foul the right rear oil line.

Regards

Dave

Unkle

@ Computamedic
If 18mm spacers are available is that something you would advise? Through dealings in the VW world lots of people run spacers to fit different wheels for the scene, but the consensus is nothing anywhere near that wide would be ideal/safe, not sure if its due to extending the load further from the bearing or if its another issue but it seems a large figure.

hawk911

spacers that large are best done with new longer bolts rather than using spacers with an already attached bolt, if that makes sense.

Computamedic

Actually, it's the reverse. There are spacers and there are shims. You will find that shims are merely used with longer studs (no wheel bolts on a 964) and are available in widths of 3 to 7mm.

Spacers, on the other hand, are supplied with their own studs and are available in widths of 15mm to a massive 75mm. These spacers are used to adjust the offset of the wheel to suit the axle design, not just to widen the track.

My own 964 is fitted with 26mm spacers at the front and 32mm at the rear to suit the BBS LM wheels and the wide body.

You can see the available shims and spacers at the Design 911 web site here.

Regards

Dave

hawk911

ok- I'll agree with the terms, but in the catalogs over here, we look for spacers and find both styles with no differentiation between the 2 styles.

Spacers search results

vtrich

semantics,...maybe use the word "adapter" for those devices that have their own
stud,..as computamedic said. "Spacer" for any thing that requires the stock or extended stud.

92silver964

Dave, whenever I get the coin to get new wheels, I am going to consult with you. I have noticed that you seem to be the wheel/tire master.

Earlydays

Just curious.....how does everyone running 18" wheels reconcile the fact that Porsche never approved 18" wheels on the non-turbo 964?

Jacke2c

The sport classic II rims will work with a 10mm spacer on the rear and none on the front. I run with a7mm on the front. I had the 7mm on the rear, and the tire would very slightly rub in hard cornering. I did install longer studs on the rear. I have been reading lots of sources about spacers/adapters and I have come to the conclusion is that different cars need different spacers/adapters. It may be a year model difference or something else such as a slight difference in the the oil return line, or build date... who knows. By the way, I love the rims until I have to wash them, it takes about the same time as it does the entire car!

sml

Thanks guys ... now I will negotiate!

Computamedic

I guess it's just a case of assessing the "risk" and making a judgement as to why Porsche made the decisions they did.

My own view - and others may have different opinions - is that Porsche Cars of America (note, NOT Porsche Germany) issued the TSB (read it here) in response to a few failures on cars running 18" wheels in the Cup racing series in order to fend off any potential legal claims should something similar happen to a consumer. The reason for the failures was not, TTBOMK, published, but it's a reasonably safe conclusion that whatever stresses may have caused the failure under racing condition (and with racing tyres), similar conditions would be difficult to reproduce under a more normal street driving situation.

There must be hundreds, if not thousands, of 964 owners running 18" wheels along with similar numbers of 993 owners who have a similar restriction with very few dire consequences. Apart from anything else - they look soooooo good!!!

Regards

Dave

Computamedic

From your username, would it be a good assumption that your car is a Turbo?? If this is the case the offset requirements of the wide body can be a little different, particularly with regard to clearance of the oil line in the right rear wheel well.

Certainly there is a difference between cars, particularly since the later cars had the offending oil line flattened at the factory.

Also, bear in mind the Turbo 3.6 cars used rear wheels with a 61mm offset (the Turbo 3.3 cars used a more usually 55 offset. However, a standard narrow bodied car will struggle to work with a 10" wheel with a 60mm offset in the rear - it needs to be 50mm or better (i.e. less) to work well.

Regards

Dave

Earlydays

I do agree....they look very good!

Unkle

@ Computamedic

And the answer to my questions is?