davs911

Any ideas for sticky competition tires on 15" wheels? Kuhmo used to make some but now I am having troubles finding any brand to fit my DE wheels.

Ed Bighi

Michelin Pilot Sport Cup. They are expensive but worth it in the long term. The longest term actually since I haven't had a track tire last longer. I use mine for street and track and have had them on since last June. Keep the hot pressures at a range of 32-36 psi. I run at 32+ psi hot front and no more than 36 psi hot in the rear. For the street I use factory pressures.

Bill Gregory

As wheels get bigger, tire selection plummets on the smaller sizes. Since you go to the track, why not upgrade to 16" Fuchs? Genuine Fuchs are some of the strongest and lightest wheels, and fit in the following front/rear combinations: 6/7, 7/8, 7/9, and 8/9 (note 8's on the front have to be the 944 8's not 911 8's. Either can be used in the rear). On my 81SC I ran 7/8's on stock 205/225 "R" tires, then went to 8/9's with 225/245 "R" tires. Fuchs look great on 911's, however, there are also other vendors that make good looking, strong wheels, too.

Michelin says negative camber should be 1.5-3.0, 4.0 max.

Here's what Michelin told me about their Cup tires (adding to what Ed posted). Wheel width recommendations at the end of note are based on my query on 225/255x17 tires for my C2:

The Pilot Sport Cup needs to run with HOT pressure in a range of 32 - 35
PSI - so cold would need to begin at approximately 7 PSI lower (to allow for
pressure increase). Your first run session should be to determine your pressure
build from cold to hot (with the hot range again at the 32 - 35 PSI range). At
the conclusion of the first run session, adjust pressures as required to achieve
the hot pressure and begin to tune for handling adjusting one end at a time by 2
PSI (so you can feel the affect of the changes in oversteer / understeer).

The traditional front-to-rear split of factory recommendations is out the window
for track applications and you may end-up with cold something like RF 25, LF 26,
RR 24, LR 25 and that's OK. Pyrometer reading have a very wide range of
acceptability for the Pilot Sport Cup at 160 - 220 F - and should be the last
thing that you fine-tune.

A couple of things to remember, tire pressure is affected by ambient temperature
by 1 PSI for each 10 degrees of ambient change. The wheel sizes for your tire sizes is a range of 7.0 - 8.5 for the front and 8.5 - 10.0 for the rear and
wider is better.

john d 81SC

Bill,

A Q re: the 1 PSI - 10 degree correlation - starting at what temp?

Thanks in advance...

aeshultz

Dave- I know The Pilot Cups are great tires- but I'm still running 15's for track wheels and have no problems finding Kumho VictoRacer 700's in 225/15

Bill Gregory

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"><strong>the 1 PSI - 10 degree correlation - starting at what temp?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Bill,

Don't know - you'd have to ask Michelin, as it's their statement.

Richard C2S

Bill and others,

I'm about to acquire an '81 SC. Couple of questions. First, without modifying the suspension, can you get 1.5 to 2 degrees of negative camber front and/or rear? I've been told that there is not that much adjustment available. Second, I'm planning to replace the torsion bars with 22/28 mms, f/r and install Bilstein Sport shocks. I will use the car on the street and do drivers' ed events. I like a very firm ride, but don't want a very harsh ride. Any suggestions? Third, I have the opportunity to borrow a set of 16x7 and 16x9 Porsche wheels off of a '95 993 until I can find a set of Fuchs for my track tires. Does anyone have any experience using the later wheels on an SC?

Thanks very much for all help.

Richard

Ed Bighi

Ok, here is what I have gathered as far as the Michelin Pilot Sport Cups are concerned. These tires are a bit different than other track tires. For one thing, they last longer than other competition tires. Enough so that I run them on the street as daily tires. I thought that Yokohama A032R's did until I tried the Michelins. Heat cycles don't seem to affect them since they not only last, but keep the same levels of grip at the end of their life when compared to new. But they seem to be more pressure sensitive then most. After some trial and error, the information at the Michelin website really made me get the most from them. I also consulted some folks who run in the Michelin Porsche Classic in England for some heat of battle information on pressures. I felt those were the best people to ask since it is a series where every car is either a 73RS, 74RS, 911Carrera3.0, and 911SC. They all run Michelin Pilot Sport Cups, since it is the spec tire, and they all run them on Fuchs wheels. I figured that even though Michelin knows their tires, I doubt they used pre-964 911's on fuchs to arrive at their data. Much less in the heat of battle. But it turns out, they are all running around the same pressures as recommended by Michelin. So I guess Michelin are spot on in their figures.

Here is what I do now. I run them on the street at the factory recommendations of 29f/34r. I take it to the track with those pressures. I run the first session at those pressures since the track surface is colder at that time. After the first session, I bring the rear down to 35-36. I don't touch the front. In fact, I never touch the front. And throughout the day, I keep bringing the pressures down to that 36psi level. By the end of the day, the front is usually at 32-34 hot. I don't want any more in the front since my car is lighter there. It works pretty well and I get excellent grip.

Richard, as far as setting up an sc for the track, here is what I think. For the street, 22-28 on the torsion bars is as far as I would go. Anything else might be too stiff for some. I drive daily on 23-30, but it is very stiff. Especially on my car which is stripped and lighter, which increases the effect of that stiffness. 22/28 is a good compromise. But if you don't mind stiffness, 23-30 is pretty effective. I used no science in my decision. I just bought the biggest solid bars made. For shocks, Bilstein Sport is the way to go for durability. They are monotube which exposes the oil to the outside wall of the shock for better cooling. For sway bars, I don't bother with adjustable. For many reasons. One, I don't give a rat's *** about a neutral car. Two, I don't have the a data aquisition geek sitting in the pits telling me what the car is really doing instead of my trying to separate what feels good from what is fast. Three, I find it much easier to adjust brain to what the car is doing that day than crawling underneath it. And when you have a car like mine which is setup to have oversteer 365 days a year, you don't have to bother anyway. The sway bars I run are regular factory 87-89 Carrera 22/21. That 21 in the rear balances out the 30mm torsion bars. I know there are people out there who swear by some high tech, super this and that sway bars. But for me, they are unnecessary. I am not getting passed by anybody with better bars so I won't get them. In the end, what is going to make you fast is to have less fear than the guy in front of you.

Don't worry about camber. A couple of degrees negative in the back should be plenty. I don't even have that much since I don't want to spoil my oversteer. As far as brakes, stock with rotors and calipers in 100% shape, steel braided lines, good pads, fluid, and dustshield removal should do fine. Notice I mentioned 100% shape. That is because a lot of the people who think their brakes are inadequate don't realize that it isn't the brakes, but in fact their condition that is bad. That is what I run and I don't have any problems. I am not getting passed by anybody who put on bigger brakes so I won't get them. As for wheels, go with fuchs. Strong and light. I run 16x7/9. Do what I mentioned above while learning how to drive comfortably past the ragged edge, and you should be good to go.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

Bill Gregory

Richard,

I'll add two cents.....On my SC, I started with 21/27's and moved to 22/29's with Bilstein Sports, and was pleased with that combination, which saw daily driving and DE track time. 22/28 is a good combination too. I did go with adjustable sway bars, as I wanted to tune the chassis towards neutrality. I want to say that I had around -1.5 degrees camber and had even wear on the tires. Hollow torsion bars. As far as wheels, the 993 wheels have around a 52mm-55mm offset, and the SC uses from 10.6mm to 23mm (36mm if you include 6's) depending on the wheel. If you want to use the 993 wheels, you'll need spacers to make up the difference. There's a 911SC FAQ on tech.rennlist.com that may answer some questions. Bruce Anderson's "Porsche 911 Performance Handbook" is another source of information.

Richard C2S

Bill and Ed,

Thanks for taking the time to respond. I appreciate help from those who have the experience. Is there enough adjustment available in the SC suspension to be able to get -1.25 front and -1.5 or -1.7 rear camber?

I'm starting with a virgin. The car has just under 35,000 original miles and is bone stock. First, gonna do the chain tensioner upgrade and pop-off, then torsion bars and Bilstein sport shocks. Turbo tie rod kit and factory short shift kit, as well as SSIs and a sport muffler will come later. Maybe 930 brakes later.

Want the car to be a terrific handling street car and more than competent on the track. I have no problem with a very firm ride on the street. Just don't want a bone rattler. This car will never be a track dog, but I hope to get about ten track days a year.

Any other comments, suggestions, tips will be greatly appreciated.

Thanks,
Richard

Bill Gregory

Richard,

Sounds like you've got good plans to create a nice daily driver that will be competant on the track. Don't forget your "r" compound tires on your second set of wheels. And if you don't have it already, a rear wing and front valance extension (need to have both together). Or new front valance to house the oil cooler you may need at the track (I found a cooler/fan in the wheel well didn't cool enough, others are OK with theirs). And the rollbar for the track, and cloth seats (I like Recaro SRD's) that have holes for the harness. Halon fire extinguisher and BK seat mount, if you don't have the rollbar yet. Weltmeister front strut brace. Convert to early 70's air source, allowing removal of engine-mounted fan. Consider removing a/c, save 50-60 lbs. Revel in being able to see your engine! Oh, and you'll want a multimeter with either a 4 cylinder dwell or a duty meter, so you can hook it up to the engine test connector to see if it's running rich or lean.

Richard C2S

Bill,

The car is riding on 16x6 and 16x7 Fuchs. I'd like to pick up a set of 16x7 and 16x8 for track tires. In the interim, I can use a friend's set of 16x7 and 16x9 Porsche wheels off of a '95 993, but will have to use spacers, which I'm not thrilled about. Maybe I'll find the correct Fuchs at the Hershey swap meet later this month. The strut brace goes without saying and a rollbar a little later on. I already have the Halon extinguisher and BK mount.

Thanks.
Richard

richard glickel

davs,

Sorry, but I won't EVER buy another set of the Michelin Pilot Sport Cups. After running with Goodrich tires with NO tire problems for a year, I tried the MPSC's, locked up the fronts before the first turn at LRP, disappeared in a cloud of white smoke and flat spotted those expensive tires (fronts).

One month later, locked them up (new fronts) at WGI while approaching the off camber left-hander, went off the track and ended up against the armco. You can blame this on the driver, I'm a big boy. Maybe you'll fare better. But this driver won't buy another set of Michelin tires.
JMTC.

Richard
'87 Carrera-3.6L

M758

I run the Toyo RA-1 on my 944-spec race car. The size is 225/50 R15 on 15x7 wheels on all 4 corners. (2460lbs & 131 hp)

I like them a lot. I feel they are much better than the Kumhos in terms of tire life, consistency and smooth breakaway charteristics.

I have not run on the Pilot Sport Cups, but do believe them to be very good tire based on Ed's experinece and that of many others.

The kumho is really good for Autocross and good on the track, but I feel there are better tires our there that will cost the same when you consider the full life of the tire.

addictionms

I too would vote for the Toyo RA1s, get them in the fall drive all winter in the rain, when they have tread, good for about 10K miles and 20 odd track days.

I have heard the Pilot Sports are too hard to getheat into with a light car, great for the 993/996 but bad for an early car.

I am running in the Toyo Cup series, so Remember Toyo sponsors 911 racing, plus they are the official tire of the Speed GT races this year again but with RA1s

check out

<a href="http://911cup.com" target="_blank">911cup.com</a>