8's or 9's? pros and cons please.
 

I have 6 and 7 x 16 fuchs on my SC. I want to move my 7's up front and get 8's or 9's for the rear. I've started doing some track days and need some more rubber. So I'm looking for some input please. Are 8's enough, tire availability, where to buy?

You should be able to find tons of threads on this subject with the search function.

I think you'll find that 8's cost almost as much as 9's so therefore focus on finding some 9's. Wheel Enhancement has/had brand new 8's or 9's for $675 each. A good used pair of 9's on ebay or in the Pelican classifieds seems to be in the $900-$1,000 range. Sometimes you can get them cheaper from a fellow Pelican member, but there are a couple of sharks in the classifieds that buy the wheels cheap and than turn them around for a very tidy profit. If you can beat them to it...

9s have a more buch and fatter look and stretch the tire out a bit more over the wheel. If you can find some 9s, I'd get the 9s.

With 8's or 9's, you will (likely) be running the same size tire, a 245. The 9's have better leverage on the sidewall of the tire, and are the better choice.

However, 9's are more expensive, and the difference we're talking about is pretty subtle. I've driven both sizes on different cars, and don't think I could isolate any difference. Back when I had stock Fuchs, I ran 7's and 8's, and was happy to spend the extra money elsewhere.

Don't you have to space the 9's on the SC? 1 inch, no? On 9's the inch is gained on the back of the wheel, correct?

No.

I think when all is said and done the different in tire print (245/45/16) between an 8 and a 9 is about 1/2". And due to the offset, the 8s sit out more, so the overall width from side to side is about the same.

I think the main difference is the 8 will have a bit more sidwall flex with the same size tire. I'm running 225/50/16 on my 8s right now, and will likely go to 245/45/16 when these are done. I was able to find 8s for a bit cheaper than 9s, although in my case I needed wheels, so I got what showed up first (without spending the extra $$$ on new 9s from WheelEnhancements).

But if I had the extra $$$ right now I'd sell my 7/8s and get 17" Lindsey wheels. But I don't. So I won't.

I don't think that there would be any difference in "tire print", my 245s on 8s make contact w/ the entire tread portion of the tire. I agree w/ Jack about the sidewall advantage of 9s.

Also, the 8s do not "sit out more", actually the 16x9s go slightly further to the outside than 8s, and the majority of the extra inch is to the inside.

The 9s are definitely optimal for 245 tires, and the best factory Fuchs size for Carrera/SC flares, IMO. You want the best tire/rim match possible and that is it, but 8s are still pretty close to optimal.

I misspoke. What I meant was the 8s sit out more than you'd expect them too...in other words, the wheel edge isn't 1" closer to the inside than a 9. mea culpa.

As for footprint, I seem to recall seeing some anecdotal information about the same tire on 8 v. 9 rim having more on the ground for the 9. Maybe I was dreaming...

Since we are comparing identical tires on different size rims, the contact patch size will be determined solely by tire pressure. Neglecting the minor affects of sidewall stiffness, the contact patch area will be the corner weight / tire pressure.

The difference in rim size will alter the contact patch shape, slightly. This due to the amount of sidewall "bulge" and its ability to distort the contact patch.

For street use and casual performance 7 & 8 is ok. For max. performance 8 & 9, 7 & 9 will be a good compromise.

Here is how the popular wheels will sit relative to the plane of the hub mounting face.
http://members.rennlist.com/1976c38/Wheel_offsets.jpg

More info here

If you are going to be a bear, be a grizzly!

If going with 8's, I'd still go with the stock 225 tire size.
(205's on 7's up front, 225's on 8's for the rear).

Another thing to consider is to just buy a matched set of 7's and 9's. That way you can sell yours as a matched set and the new set should match if they were originally a set.

One thing I do like about the nines is they do move out closer to the fender lip about 3/8th in. thus filling it a bit better.
If your SC or Carrera is lowered with this set up they look pretty Fat in the back. A big difference from the stock look. Maybe? even better than a Turbo with the same sized wheels :rolleyes:

I'd like to thank everyone for their input. It looks like 9's are the way to go and if anybody wants to sell me theirs I will put them to good use.

Or go 8's in the front, then 9's in the rear - that's the best answer...

951 8's, that is.

Thanks Jack -
to clarify -
Porsche Part # 951 362 117 00 16 x 8 Fuchs

if I had it to do over again, I'd buy 9s.

But the slope is slippery, so once you get 9s, then you start thinking about 17s and going 8/9.5...