KY-91C2

Hello all:

I was wondering if anyone could recommend Autocross tires for a 91 C2? I typically do between 8 and 10 autocrosses a year. Since I only have one set of wheels, I will need to use these tires on the street, too. Typically, I only drive the car in nice weather, but occasionally (usually for an auto-x) I get caught in the rain.

Currently I have 205/50ZR17's on the front (7Jx17 wheels) and 255/40ZR17's on the rear (8Jx17 wheels).

Thanks in advance for any suggestions.

Ron

91 C2 Cabriolet
85.5 944 NA

Rick964

I run the Kumho Ecsta MX on my 90 C4 for autox, DE and street and really like them. Excellent grip, good durability, and great price.

KY-91C2

Rick:

Are your running on 17" rims or 16"? I checked Kumho's site, and they do not have the Ecsta MX's available in the front tire size I am currently running. If you are running 17's, what size tires are you running on the front and rear? I assume you have had no problems with them.

Unfortunately, I do not know much about tire sizing. My next task is to do some research on this. For instance, could I use a 205/40R17 on the front? Or is it hit and miss, and do i have to try them to see if they will work correctly?

Thanks,

Ron
91 C2 Cabriolet
85.5 944 NA

HarryD

One way to see what tires you want is to go to an AutoX and look at what the fast guys are running.

Rick964

I run 17's. 225/45 in front and 255/40 in the rear. I have 7x17 front wheels and 9x17 rears off of a 996 and this is a very common setup for C2s and C4s. Some guys are able to get 275s in the rear but you will need spacers to keep from rubbing. Do some searches in the 964 forum for tires and you will lots more info.

jim944s2

If you're going to auto-x in the rain, get Bridgestone S03's. Lots of other tires are good for dry, but those are proven winners (in stock category) in wet and dry conditions.

ceboyd

Yes, I can vouch for that! I used S03s last year exclusively for track AND autocross and for a street (non R compound tire) they are really difficult to beat!

I heard others rave about the Falken Azena's (the ones with the funky tread) but they look like they might be extremely noisy and I have no personal experience with them. I talked to folks with them who had them for their Mini Cooper, BMW, Integra, VW and some Honda owners at SCCA autocross events.

jim944s2

The Azenis' are the way to go, IF they are available in your size. I've heard that they are in-fact a Yokahama 032R w/ Falkens name and tread pattern.

PedalFaster

The Falkens are definitely up there, but there are lots of other street tires that are just as fast. The real selling point for the Falkens, and the reason why they're so popular in SCCA Street Tire classes, is that they're cheap.

A tire to consider if you're willing to cross the line into R-compounds is the Toyo RA-1; it's probably the most streetable of the R-compound tires (I know a lot of people who use it on their daily drivers), and although it won't hold a candle to a full-on race tire, it'll be significantly faster than an Azenis, S-03, or other true street tire.

Steve

KY-91C2

Ok. I'm down to three potential tires. The PS2, the Pilot Sport Rib, and SO-3's.

I found out this weekend that the PO did not change the steering stops on my 964 when they mounted the 17 inch rims. Looking this weekend, I see that I have had some tire rub on the inside of the front wheel wells. That being said, I want to stay with 205/50's on the front (eliminating many tires from the running), as 225/45's seem to have a greater overall width. I believe that the tire rub is only a problem on very tight turns, such as those on an autocross course. When I get the chance to change the steering stops, then I may consider the 225's.

I don't believe that the PS2's are available in 205/50's yet, but I may be mistaken.

Can anyone give any comparison on these three tires for Auto-X / Street use. I've read many reviews on the three, and "best" tire seems to be quite subjective. Noise is not a concern. Maybe it is to my wife, but not me . However, I'd like to compromise between Auto-X performance and safety on the street (especially if I get caught in the rain).

Ultimately I know it is a gamble, regardless of what I choose. Currently, the car has Sumitomo HTR Z's, which were present when I bought the car two years ago. I suspect any of the above will be an improvement, since they are at least 2 1/2 to 3 years old, if not older.

Thanks,

Ron

91 C2 Cabriolet
85.5 944 NA

chris walrod

Anyone know when the PS2 will be available in 255/40/17?

I have my eye on these tires as well!!

joey bagadonuts

I have a slightly different take on auto-x tire selection.

First of all, wide rear tires in conjunction with skinny fronts will induce understeer--fatal in autocross--so avoid them. If you're set on 205/50/17's up front, you should consider 225/45/17 rears. BTW, those are the original tread widths fitted to the 964 (albeit on 16" wheels).

Along with minimizing the width stagger, make sure you pay close attention to tire pressures. I've performed G-Tech tests and pyro'd street tires at the track and they perform best at over 40 psi. I was measuring continuous later g's with the G-Tech and grip dropped off significantly on my P-Zeros as pressures dropped below 40. At the track, pyro temps clearly indicated that low to mid 40's was the sweet spot.

For every day driving, 36 psi front and rear are fine, but when you line up for your timed runs, your pressures need to be at or near the optimal setting given the lack of warm up time.

jim944s2

Joey, have you tested other street tires like you did the Pirellis? Also, how warm was the outside temp and the pavement during your tests?

joey bagadonuts

No, just the Pirelli's. The G-Tech test was on a warm day, approx 80F. Pyro readings were taken during a track day last Fall with temp in the 40-50F range.

For perspective, I run R compounds in the 34-35 psi range hot (cold pressure is 28 psi). Tires I've used include Kumho Victoracers and Michelin Pilot Sport Cups and I used a pyrometer on both to determine best hot numbers.

Due to their softer sidewalls, street tires need more pressure to prevent excessive rollover. My car weighs approximiately 3,000 lbs, so if you have a lighter car, you may want to run 2-4 pounds lighter to allow more flex and heat generation. If you are serious about dialing in pressures, I'd highly recommend that you purchase a pyrometer.

jim944s2

I probably should buy one, I run S03s in Stock category autox on an '89 944S2. The seat-of-thepants-o-meter seems pretty happy at 33 or 34 warm. Most of the stock tire 944 guys of similar weight seem to agree. I've tried higher pressures and it just doesn't seem to work, but the pavement we run on is usually cold (and a bit mossy).