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Posted by: silver six Feb 10 2003, 05:26 PM

I'm thinking very seriously about trying to get a set of Porsche Design 90 Aluminum rims under the fenders of my 914-6.

See these webpages to remind yourself what the Design 90s look like:
http://www.wheelenhancement.com/Design.htm
http://www.porsche964.co.uk/rev_rep/aufwheels.htm

My fenders have not been flared or rolled. Right now I have 5 bolt Fuches on 195 R 15 (I think they're 15s; I don't remember for sure).

Will the Design 90's fit?

Thanks in advance,

Douglas

Posted by: Mueller Feb 10 2003, 06:45 PM

The 6's and 7's will fit with the use of spacers.....

First picture is a 16x6 with a 205/55/16 tire....it needs a spacer to look right other than that it fit fine...a 16x6 on the rear would work as well....I'd recommend same size tire, but you'll want a spacer to move the wheel out a bit to look correct.

The 7 will work with the same size tire.....you'll have to use a spacer that will bring the offset to 35mm for stock fenders....not sure what spacer to use for the 6" rim, but I'd guess a 1" spacer would be just about right.

Second picture is a 16x8..it hits the trailing arm, but not by much, something could be done about that

Posted by: silver six Feb 11 2003, 12:25 PM

Mueller,

Thanks for the advice and the pictures. That's really cool.

Additional complications: First I have black four piston calipers from a 944 with vented rotors in front and the 914-6 solid rotors (that used to be in front) now in the rear. The front brakes are a tight fit but the PO added washers at each lug stud, behind the wheel and that allows the Fuches to clear the brakes without scraping the "Porsche" letters off. In addition, the car has been substantially lowered. In front the torsion bars are lowered to maximum lowness. In back, 165 lb springs have been installed--with accompanying shortness (I think an inch or maybe 1 1/2 inches shorter than stock).

So I imagine that getting the Design 90s under there will not be easy, if possible at all, without raising the car back up to stock height.

What do you think?

Douglas

Posted by: Mueller Feb 11 2003, 01:02 PM

Get rid of those damn washers as soon as possible!!!!!! the load is not being evenly distributed to the wheel and hub surface....the wheel can be damaged from this !!!!

okay...off of rant

Since you'll be running a small spacer, you shouldn't have problems with caliper clearance.

Guessing that you are running 195/60/15's...you'd want to go with 205/50/16's on the new rims....the diameter on both is ~24.1 +/- .1 inches

You should not have to raise the vehicle at all......just go with a tire that'll keep the same (or close) diameter.

The 6" rim would be the safer choice so that for sure no fender modifications need to be done. It might also be easier and cheaper to find 6" rims for these cars.
(standard front rim width on the C2's)

Here is a web site to plug in your tire information to play with:

http://www.miata.net/garage/tirecalc.html

Posted by: SirAndy Feb 11 2003, 01:13 PM

hey, pretty cool link müller ...

it says that running my 225/50 x 15 effects the speedo-reading by only 1% !!! (too fast)
meaning when my speedo shows 100mph i actually
only go 99mph. not bad, guess i can live with that :-)

and the 295/40 x 15 i'm planning on running are even better!
only 0.8% (slower) ...

Andy

Posted by: jonwatts Feb 11 2003, 01:18 PM

It should have a disclaimer saying if you have a Porsche 914 then your speedometer is probably off by 20% anyway so don't worry about it.

Posted by: SirAndy Feb 11 2003, 01:27 PM

good point. i run a 944 speedo anyways ...

Posted by: J P Stein Feb 11 2003, 01:29 PM

Andy:
I'm running 225 X 50 X 15 (Vracers) and my speedo is off bout 15%(WAG). 70 indicated is 60ish.
Tire diameter is 23.5 inches. 205s are an inch shorter.

Posted by: SirAndy Feb 11 2003, 01:39 PM

i compared to 165 HR 15 which is the stock wheel size.
the little gizmo on the website told me that my 225/50 x 15 were only 1% off. dunno ...

Andy

Posted by: Dave_Darling Feb 11 2003, 04:50 PM

Remember, Andy--JP still has a 914 speedometer!

--DD

Posted by: SirAndy Feb 11 2003, 04:52 PM

oh, you mean the one that came with the factory tolerance of 20% ????


Andy

Posted by: silver six Feb 11 2003, 05:28 PM

Mueller,

Thanks again for the advice.

One small correction. I'm actually running 205/60 R 15s. My bad. I assume that does not change your analysis and your ultimate conclusion. I have an apointment with a wheel shop next week and I will tell them to get rid of the washers, per your advice, and replace with the proper spacers.

As a side note, the Factory Porsche manual says that the 914-6 came in either 165 HR 15 (646 mm total diameter) or a 185 HR 14 (at 650 mm total diameter). Ironically the tires on the 15 inch rims were actually thinner and of a smaller diameter than the tires on the 14 inch rims. I'm not sure why that was so. In any event, using the convenient converter you linked me to I discovered that to get similar overall diameters in a 205 tire running a 16 inch rim I could go one of two ways:

(1) either I could go with a 205/55 R 16 which would give me a total diameter of 645 mm (only a fraction of a fraction smaller than the factory's 15 inch rim configuration, but a full 3% smaller than the factory's 14 inch rim configuration); or . . .

(2) I could go with a 205/60 R 16 which would give me a total diameter of 652 mm (only a fraction of a fraction larger than the factory's 14 inch variation, and only 1.1% larger than the factory's 15 inch variation).

So what do you think? Am I better off with a total diameter just a little bigger than the largest stock size diameter, in the middle of the two stock sizes, or a fraction smaller than the smallest factory stock size diameter?

As a side-side note, the factory 914-4s came in either 632 mm (155 SR 15) or 646 mm (165 SR 15) diameter variations.

Douglas

Posted by: Demick Feb 11 2003, 05:38 PM

Either should work fine. It really depends on what kind of tire you want to buy. If you are leaning toward performance, you will want the lower profile tire. In fact, high performance tires won't even come in the 60 series. The 205/55-16 is a very common size for a large variety of performance levels. Lots of tires to choose from. That's what I would go with (or I should say that's what I put on my car).

Demick
'74 2.0

Posted by: Brad Roberts Feb 12 2003, 03:21 AM

I just noticed Demick's avatar is in the water..LOL Great shot. I have nothing to ad about the tires.. Thanks for joining us Demick. I know you have a lot to offer this group.

B

Posted by: Demick Feb 12 2003, 09:08 AM

Thanks for the welcome Brad. That shot was taken at the 1st GGR autox last year at Candlestick. Weather was horrible and there were sections where we were drviing through lakes. Check out how bad it was with the pic below. I did manage a 3rd fastest time of the day though