Widest/tallest tire- 205-65-15 fits perfect

[wkrtsm]

Was in need of a tire upgrade, so started looking for extreme summer performance types. (in Texas -->9-10 months of heat/year, car is not daily driver, only sunny weekends with near-zero rain probability, car hasn't seen water in >25 years).

Regarding sizing, I did some calculations using the recommended OEM tire diameter of 23.25" for 912s. The car had 205-60-15s, but the goal was to keep engine RPM down more at high speeds on freeway (I don't rally, or race on a track), so I went with a slightly taller tire, which is 205-65-15. When I did some calculations, the 205-65-15 will be something like 7 cm ahead of the 205-60-15 per revolution, which, for the same RPM adds up to a lot more distance covered. Indeed, based on perception, the RPM is lower for similar speeds on freeway. There's also plenty of room between front and back fenders and they work fine.

As far as performance, they're not bad for handling and cornering. The brand model I chose was BF Goodrich, Advantage T/A Sport. Originally, I wanted Michelin Pilot Sport 4S or Firestone Firehawk Indy's, but many of the top-rated summer performance tires are not available for smaller width's and/or 15-inch wheels. (fyi BFG is owned by Michelin, so it's a high quality tire).

BF Goodrich - Advantage T/A Sport (on back):



BF Goodrich Advantage T/A Sport (on front):



Michelin Pilot Sport 4S (205-65-15 not available):


Firestone Firehawk Indy (205-65-15 not available):

[cmpski]

The factory SWB tire was 165/80/15 at 25.4 inches and later a lot of folks chose to go to 185/70/15 at 25.2 inches. The 195/65/15's are 25 inches.
I have 195/55/16 Firestone Indy 500's on 6X16's at 24.4 inches. I had 205/55/16's at one time but I didn't like the look. There was only about 3/16's rear clearance. It look weird. Just too tight. I went with 16's for the tire choices.
The Indy 500 is sold as a Bridgestone in Europe.

[cmpski]

Firestone strongly supported Porsche Racing in the late 50's, 60's, and early 70's. The first 917 test was run on Firestones.

[wkrtsm]

With 16" inch wheels, I can see having issues with clearance depending on what tire size is employed. The aspect ratio of 80 is also believable for a rather thin tire. Thanks for the pics and info on Firestone! I know a lot of new Porsche's have Michelin, and there are cases of Pirelli's as well, but none of those have 15" wheels for which extreme performance summer tires are almost totally unavailable.

[wkrtsm]

The catalog pic of the BFG's I purchased was about as sporty as I could find for 205-65-15. They do have a flatter wall, which is less bulbous than other choices. I also didn't go with e.g. Toyo's, Yokohama's, Kumho's, since BFG is Michelin -- and I'll take Michelin over other manufacturers any day (Michelin are also popular for OEM on euro cars). Also called Summit Racing, and their most popular tire sold is the BFG Advantage T/A sport.

[cmpski]

Both the 6X15 and 6X16 Fuchs have the same 36 mm offset. The 15 inch tires usually have a rounder shoulder than the 16's hence slightly better clearance for 205's on a SWB car. The SWB cars were slightly more hand built than the LWB cars. Therefor fender clearance differed a little car to car. The LWB car bodies were a little more consistent car to car.

[BK911]

I just picked up a 68 with 205.55.16s.
Looks like a matchbox car.
Way too much wheel, and 40#s at each corner.
Guess it matched the whale tail!
New 15x5.5 rims on the way.
Probably going 185.60.15.
About an inch shorter and about 12#s lighter each corner!

[Boehm]

Originally Posted by cmpski

The factory SWB tire was 165/80/15 at 25.4 inches and later a lot of folks chose to go to 185/70/15 at 25.2 inches. The 195/65/15's are 25 inches.
I have 195/55/16 Firestone Indy 500's on 6X16's at 24.4 inches. I had 205/55/16's at one time but I didn't like the look. There was only about 3/16's rear clearance. It look weird. Just too tight. I went with 16's for the tire choices.
The Indy 500 is sold as a Bridgestone in Europe.

Thanks for the information, keep sharing this type of info

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