m5guru

I am in the middle of a search for a set of winter wheels for my 2002 C4 Cabriolet.

It seems that my two basic options are 17 inch wheels in 7 inch and 9 inch widths versus 18 in wheels in 8 inch and 10 inch widths.

Will there be a significant difference between the same tire in these sizes? Certainly, it seems that matched sets are easier to find in the 17 inch sizes.

I've got a lot of questions about offsets too. There are a lot of 17 inch front wheels with 55mm offsets, although the manual recommends 50mm offsets. Do they even make 5mm spacers? Seems awfully narrow for a spacer. Does that difference make any difference? These fronts usually are matched with rear wheels with the correct width and offset. I think these sets come off of Boxters but some also say they come off of 996's.

Thanks for your guidance.

David

neil.schneider

Call tire rack for their opinion. I think 17s would be the way to go and cheaper too.

TT Surgeon

Sorry, you're not allowed to discuss winter until after Sept. 1st.

m5guru

Bet winter-related things get a whole lot more expensive around then too! :-)

yetis

Diligently watch Ebay. I got a whole setup of stock 17 rims with winter tires for $600. There is still significant tread left, even after one season. I think you want 17's for the sole reason that roads quality declines dramatically in times after September 1 . So any major pot holes, or other nasty surprises that might taco your 18's, would not impact the 17's as much. Also, 17's are cheaper to replace. I guess it would also matter where you are located and how often your car is such weather.

m5guru

I have been watching eBay. I do see some good deals on wheels. But it seems that the offsets are usually off by 5mm either in the front or rear. What are the offsets of your wheels? Do you have a C2 or a C4? It has been implied that the C4 is pickier about the wheels front-to-rear.

Here in the DC area, there are only a handful of days with really bad weather. And maybe a couple of weeks worth of days with any significant snow lying around.

David
--

RJMDAD996

I use M3- Winter sports mounted on Millie Spiders "18 - nothing but perfection in the snow. !

m5guru

What size tires and what offset are the wheels?

Thanks,
David

bavarian

I got my Mille Miglias from Tirerack with 17s--I would check with them first concerning the offset etc. I drive a C4S, so it's different. The smaller diameter gets better traction and allows a greater selection of tires. I ended ujp with Blizzak LM25s because the Dunlops were sold out, and it was a great choice.

stiles_s

Late 996s (2002+) offsets are (IIRC):
17: x7 (et50) x9 (et55)
18: x8 (et50-52) x10 (et65)

Earlier 996s had different offsets. i believe they ran 55mm in front. If I were you, I'd stick as close to the '02+ factory offset as possible.

Also, I wouldn't trust the random bozo you get on the phone from TireRack as the expert. What they know is binary: it fits or it doesn't. Fits means it doesn't rub.

Oh, and yes you'd be better of with 17s in the winter, though I ran 18s without a problem.

Finally, Porsche makes 5mm spacers with new bolts/locks if you're interested.

jittsl

I have a set of 17 inch wheels mounted with Dunlop snow tires (205s and 255s) which I ran on my 01 996 C4. As the 996 is now a dedicated track car they are redundant. If you are interested email me at laurence.jitts@verizon.net and I will respond with greater detail and pictures. The wheels aren't perfect but they are certainly straight and the tires have 80% tread. they are also located in Boston so the shipping should not be too bad to DC.

m5guru

Yes, you are right about the factory offsets for the 02+ years. That is what they state in my manual and what I've seen posted elsewhere. Furthermore,that's what I have on my car! (Doh! Didn't think to check that already, did we? :-)

I was going to try to avoid spacers if possible, but it's good to know that Porsche makes that option available.

It seems that I read somewhere that Porsche authorizes the fitment of 11" wheels on the rear with 63mm offset. Although the wheels that come on the widebodies from the factory have a 45mm offset, so they definitely can't be used.

David

m5guru

These are the offsets and sizes of Laurence's wheels mentioned above:

rear = 9 x 17 ET47 with 255/40/17 Bridgestone WT-05 winter radials
front = 7 1/2 x 17 ET52 with 205/50/17 Bridgestone WT-05 winter radials

Compared to a set of wheels with these sizes:

rear = 9 x 17 ET55
front = 7 x 17 ET55

Which set (or either or neither) would be appropriate for a 2002 C4?

I have seen various sources of "approved" wheel sizes and one even listed both 50 mm and 55 mm for the front offset in 7 in widths on 17 inch wheels. Just don't know what the source of that table was. I found it on Renntech.org. This same table also "approves" of 5mm spacers on both the front and rear axles with 55mm offset wheels in the stock 17 inch sizes.

It's tough buying second hand wheels!

Thanks for your thoughts.

David

stiles_s

IMHO I'd stay as close to the stock 55mm front offset as possible, to preserve steering geometry and feel. Deviating from stock offset in the rear is going to less obviously affect the way the car drives, though I still would recommed staying w/OEM offset.

m5guru

Unfortunately, stock front offset is supposed to be 50mm.

At least that is the most commonly quoted number I see and the number that is mentioned in my manual.

But as I said, there are some other sources of information that make it sound like 55mm offsets are acceptable as well for the fronts.

Did anyone buy their car from the factory with 17" wheels and get 7 inch wide rims with 55mm offsets from the get go?

My impression is that a lot of these 55mm offset front wheels are coming off of Boxters.

David