Tire Size ?; Fuchs 8 & 7s/16

Mookster · Mookster's Garage

I just purchased a used set of 8's for the rear of the ole 1983 SC. I am beefing up the stance for the holidays.

I have searched the archives and could not get a definitive answer on what tire sizes to run in my new setup. My fenders are not rolled and I do not wish to perform this procedure.

I am currently running Potena S-03 225/50 on the rear 7s
I am currently running 205/50' on the front 6s. The front tires need to be replaced.

The 225/50 are in good shape and relatively new.

As I transition the new 8s to the rear and the old 7s to the front what tire sizes should I be running on the 8s & 7s with this new setup?

As always, your help is appreciated in advance.

PorscheGuy79 · PorscheGuy79's Garage

I have 205s up front and 225s out back with my 7s and 8s. They work very well. I had 6s and 7s with the same tire combo and I found that it gave you too much sidewall. You can also put 245s out back but some tires dont come in that size. Good luck to you.

450knotOffice · 450knotOffice's Garage

I have 7's and 8's with 205's up front and 245's in the back. The 245's fit perfectly on the 8's and I have no rubbing issues. Oh, and I have S-03's.

Mookster · Mookster's Garage

Thank you for your responses

rfuerst911sc · 11-12-2005, 09:53 AM

I have a 83SC and with 7+8 Fuchs I run 205/55 and 245/45 with no problems. I also run 17's ( just installed today ) with 225/45 + 255/40 with no rub issues either.

porschenut · 11-12-2005, 09:56 AM

I run 7's and 8's with 225 in the front and 245 in the back. Save yourself some money and keep the 225's on the 7's. You won't get any rubbing unless you drive on the track.

KobaltBlau · 11-12-2005, 10:26 AM

Quote:

Originally posted by porschenut
Save yourself some money and keep the 225's on the 7's. You won't get any rubbing unless you drive on the track.

I assume dave is referring to the front of the car. Just a warning, I got rubbing driving on the street with 225s on 7s on the front. These handmade cars vary, though.

jester911 · jester911's Garage

I have 225's on the front of my car. I did have a small issue on the drivers side. When going into a hard lefthander that
had a bump in it would cause it to rub just as the front suspension was compressed. I rolled the fender a bit and no more problem.

It sure feels more stable with the wider track. Not to mention more aggressive looking

porkersc · 11-12-2005, 02:58 PM

Hi guys. I run 6's & 7's what tyre size could i use to try and reduce the sidewall height. All 4 due for replacement any ideas?

anthony · 11-12-2005, 04:53 PM

Quote:

Originally posted by Mookster
My fenders are not rolled and I do not wish to perform this procedure.

FWIW, I had to roll my front fenders with just 205s. I'm at Euro ride height.

drsimonwong · 11-13-2005, 01:51 AM

I had to roll my fenders too with 205's up front though with Chuck's decambered joint widening the track further. Fair bit lower than Euro height.

Wavey · 11-13-2005, 04:29 AM

One of my goals was to get the front sidewall heights to be equal to or less than the rears. I wanted to run the 245/45s on the rear in order to get the extra 1.1" of tread width over the 225/50s. Yokohama says that the 245/45 is suitable for rim widths of 7.5" to 9" so I figured I'd be OK with 8" rims.

I have 7" rims on the front with 205/50 tires. The 205/50s are 24.1" OD, which is .9" less than the OEM size, but the tread width is the same at 7.5". I was a little hesitant to go this route, but I reasoned that the smaller OD would provide a little quicker turn-in. This made me wonder if I'd get more oversteer, which reinforced my decision to go with the 245/45s on the back, reasoning that I could use the extra grip back there. The 245s are 24.6" tall and 9.4" wide at the tread. Sidewall heights are 103mm front and 110mm rear, which is exactly what I wanted (visually).

The turn-in is definitely quicker. With the OEM wheels/tires, which were the same Yokos, there was a tiny delay between the steering input and the point where the front end took a set. Now it's immediate. With the 245s and the extra 2.2" total tread width, the tail just hangs on forever.

However, if you're going to be lowering the car, the 205/50s can be problematic because they lower the front end .45" all by themselves.

porschenut · 11-13-2005, 06:12 AM

Quote:

Originally posted by KobaltBlau
I assume dave is referring to the front of the car. Just a warning, I got rubbing driving on the street with 225s on 7s on the front. These handmade cars vary, though.

Yup, and other factors come into play also, like alignment settings, ride height and driving style. I never get rubbing on the street, but I do on the track (even with rolled fenders).

Wavey · 11-13-2005, 08:12 AM

I'd like to add that bigger isn't neccessarily always better. A larger tire will generally weigh more and have a (slightly) negative effect on unsprung weight, and you can loose that nice nimble feeling in the steering without gaining anything else.

Wil Ferch · 11-13-2005, 11:47 AM

Andy(Kobaltblue) says.....

...."I assume dave is referring to the front of the car. Just a warning, I got rubbing driving on the street with 225s on 7s on the front. These handmade cars vary, though..."

I respectfully disagree. Porsche has some of the most precise and accurate body parts in the industry. This "hand built" stuff we all (wish) were true ...is actually "hand assembled" during this era. Hand-built...with all its variations... was done in Gmund.

Now...that isn't to say the cars were built "symmetrical". It's very likely the driver's side of a typical 911 rubs and the psngr side doesn't. It only means that the "master" dies for these cars were not the same left-to-right... wheeby almost ALL are like that.

The likely real culprit is the wide variation in tire sizes and shoulder shapes...among the various tires. This can account for 90% of the reason some say "X" fits and others say "X" tire doesn't.

Wil