Just so we have the terminology straight, when referring to spacers, my understanding is that:

• Hub-centric means that the spacer itself is designed to fit perfectly on the factory hub lip, as opposed to a spacer that just centers on the lug bolts.
  
• Wheel-centric means that the spacer has an additional protrusion lip that the wheels can sit on. I've never seen this in 5mm spacers, as the factory hub lip still protrudes past a 5mm spacer. I think most 7mm spacers are also not wheel-centric.

 

I used http://www.motorsporthardware.com/porsche/ and was very happy with them. I have had no problems with vibration or shaking of any kind. Currently running the 7mm with extended bolts as well.
From my understanding they make a lot of the H&R stuff.

No affiliation

 

FVD 7mm spacers are wheel centric. Call them.

 

Hi guys - I know I know - don't always listen to the dealer, but I was talking to the shop foreman at my dealer who I really trust (not the service advisor). He said that on Porsche cars with existing warranties and using OEM spec wheels, the factory will not warranty wheel bearings or suspension components on anything with over 5mm spacers in the front. (rears can go up to 17mm)

That's why Porsche only recommends maximum 5mm spacers in the front with factory wheels and 17mm max in the rears.

The 17mm do kick up a ton of dirt on the sides of the rear bumper so I am going to go with 5mm Porsche OEM spacers all around.

I know many of you have gone with 7mm without problems - but I looked into the price for 7mm spacers with wheel centric flanges and for a complete new set of longer, locking two piece bolts and they're all coming in more expensive than the Porsche 5mm set.

For a 2mm difference, I figure I'll just go with the Porsche 5mm set.
And finally I saw this post from an old timer and that sealed the deal for me. Perfect amount of extension without looking over done...

 

Would not even buy 5mm spacers and waste the money. I would buy wider rubber instead to get the benefit of extra grip and look as extra. IMHO

Here is my old car sitting on 7mm rear and 15mm front FVD spacers

https://rennlist.com/forums/8451182-post8.html

 

ALways admired your car and the stance!
Anyway I know I'm probably being too conservative but I really do like the various 5mm spacer pics I saw online from at least a half dozen owners...so I placed a call to Sunset Porsche in Oregon - they have it on sale for $300!

Will post before/after pics

 

+1 on 7mm, 15mm FVD... another thing to consider is the lug nuts, make sure it is a 2 piece utilizing a floating collar.

 

If running oem specs on wheels, 7mm front and 15 rear will be perfect. If you put 15 on front, the tires will rub the inner wells at full lock, unless you use a heat gun on the wells and then it should be fine. 7/15 is the easiest.

 

not true, many people run 15mm up front and 7mm rears... with no issues.

 

I also bought the FVD Brombacher hubcentric 7MM (actually 7.5mm, IIRC) all around, and they come with high quality longer bolts as part of the price, as well as the screw that holds the spacer in place to the disc for when you remove the wheels. Smooth as silk, no extra balance wieghts were even required. Highly recommend. I've got a post with pics on here somewhere. Especially noticeable if you lower your car at all, like I did with PSS9s.

 

Thanks all.
I decided to follow my master techs advice and be conservative
Went with the Porsche Oem 5mm kit with new security bolts.
Hopefully weather is good enough tomorrow for me to install them and put the winter set on

 

Here are the winter tires and wheels w/ the new Porsche 5mm spacers.
One thing I noticed about the OEM 5mm spacers is that they're not simply flat. The area around the center hole is machined to allow the hub's flange to protrude all the way out to make sure the wheel is hub centric.

 

Personally 5mm isn't worth the hassle/cost on a factory offset wheel for the 996. The main reason to have spacers is for looks and I don't really see 5mm making any noticeable impact in that department. But if you're happy with them, that's all that matters.

 

^^^ +1

5mm-7mm are flat and uses the cars built in flange to be hubcentric. They are to thin to make with a hubcentric lip because of this flange. So, it's not a OEM Porsche magic thing. 14mm is where it starts for the spacers to have its own flange to be hubcentric.

 

I went with the Otis 7/15 mm package with bolts and couldn't be happier. Huge improvement in looks, no vibration. Quick shipping from Otis, they even called me prior to shipping to insure that I was running OEM wheels so they sent me the correct seat lug bolts.