Steve87-911

So just what were original rim sizes for a U.S. 87 Targa? 6s and 7s? Were 7s and 9s a factory option for non-turbos? My tires are supposedly the original size and they are front- P205/55ZR16 and rear- P225/50ZR16. My owners manual implies that the corresponding rims are front - 6J x 16 and rear 7Jx16. Do you think my rim sizes are original sizes? I assume so since everything else on this beauty is stock. My polished Fuchs look awesome and they look wider than 6s and 7s, but what do I know.
Thanks,
-Steve

Dane

Jack this is my first hand experience and not more info gleaned from the net.

I used a postal scale to first weight my 7 and 9 Fuchs with Bridgestone RE750s, 205/55/16s and 245/45/16s. RE750 tire diameters are 24.9" and 24.6". Then I weighted my 8 and 9 Fiske 10 spokes with SO3s, 235/45/17s and 255/40/17s. SO3 tire diameters are 25.3" and 25.1".

The fronts were bigger weight gain on the Fuchs than the slightly slightly heavier rears with the Fiskes. Much of that was because of the 235 tire size and the 8" rim is a jump on the 205/7". Total overall gain from the lighter Fuchs set up and the heavier Fiske set up was 34# and change. Again IIRC something like 7# in the rear and 10# up front for each wheel and tire.

The tire patch gain (heavy rubber tread) is over two inches in the front on this comparison and almost an inch in the rear. The SO3s weigh more. My impression, but I didn't get to weigh the wheels without tires, is the 9" Fuchs and the 9" Fiske's were very close # wise.

The 17" rear wheels gained 1/2 an inch in size over the 16s. Which would effectivly give you taller gearing. Upped my top end a bit, 7mph at 7K, again, IIRC by the gearing chart.

Much of differences can be dimished by careful selection of rim and more importantly tire size. (and yes the custom two piece welded Fuchs seem to be very light in comparison to either stock wheel in this comparison)

The difference in the larger tires on my car was noticable on the track. The gain in tire patch was impressive for braking but the loss of felt torque on a 180hp engine was not.

Brakes? VCI will tell you that the 930 calipers normally need to be trimmed to fit 7" Fuchs. They actually show them on the web site trimmed last I looked and I know mine had to be trimmed a good deal more to clear the 7" Fuchs.

Here is a classic example of trimmed 930 brakes for a set of Fuchs. This is many times the best case scenario. Adding spacers and shaving brake cooling fins should be your first indicator that you are not using the best engineeering available.

http://tech.rennlist.com/911/Street_Track_Mods2.PDF

A quick look at Porsche design and developement will clear up the issue of 7 and 8" Fuchs fitment on the front of our modified cars. It isn't perfect and can easily be bettered. I don't consider a 205/55 the best set up today. Didn't take me years to figure that out

Steve?

Yes the 6 and 7s were factory. 7 and 8s and 7 and 9s were factory Turbo and Turbo look set ups.

Bill Verburg

I don't know how these things take on a life of their own, totaly off topic, Yes, the 7&9x16 are a great setup, yes the 9s are worth the extra $

205/55 or 205/50 will fit on the 7s w/ few issues,225/50 is harder 225/45 solves most of the /50 series issues. 245/45 is a great choice on the 9s

more wheel info