joey bagadonuts

So far, I've had three sets of MPSC's on my C4.

Front: 225/45/17
Rear: 255/40/17
Primary Use: Track Days
Target Hot Pressure: 36 psi (all around)

1st Set
Source: Bought new from Tire Rack.
Heat Cycled by Tire Rack: No
Camber: -2 degrees front and rear
Performance: During their first 20 minute session, the tires were very slippery. After a 90 minute rest, tires showed significant grip improvement during the second run. By the third session, the tires were performing at their peak, IMHO.
Wear: 25 heat cycles. Corded front outside shoulder. Normal for track tires.

2nd Set
Source: Bought used along with track wheels
Heat Cycled: No Info
Camber: -3 degrees front and rear
Performance: Good grip. No issues.
Wear: 32 heat cycles, 10 by previous owner. Corded inside front shoulder. Probably due to heavy throttle during understeer (remember, the front wheels on my car spin).

3rd Set
Source: Bought new from Tire Rack
Heat Cycled: Yes
Camber: -3 degrees front and rear.
Performance: Unlike the first set, the heat cycled tires showed impressive grip from the very first session.
Wear: Still look new after four, blistering 25-minute sessions.

If I can go keep the understeer in check, I'm hoping the 3rd set will last 35-40 heat cycles. Unfortunately, I can't clarify whether heat cycling or the additional camber improved the longevity of the 2nd set. But what I can confirm is that heat cycling made a significant difference in initial performance which meant I didn't waste any track time breaking in a new set of MPSC's.

I'll let you know how long this 3rd set lasts.

Questions?

AsianBond

I just bought a set of MPSC, hope they are as good as everyone says they are. I noticed my set are a bit older, manu. in 2001, any differences?

tonytaylor

1) Do you think they take longer/ need more heat in them the more heat cycles they have?
2) How many track miles do they last?
3) Do you think -3deg neg camber is too much? I'm running -3 on my present set and am concerned that inside wear is more than outside. At -2 had equal wear across the tyre. Do you have a pyrothingy that shows -3 as the optimium?
4) 36psi seems high for MPSC, is this the result of using a pyrometer? I'm currently running F30/R32 hot. (although I probably weigh hundreds of lbs less than you )

RSAErick

Good write-up, Joe. It looks like you've corded your last 2 sets prior to getting all of the heat-cycles out of them. Any word on how many heat cycles they might have in them before turning to rock? I have about 25 heat cylces in mine right now, and still have tread on them. I thought that I might lose them to heat cycles before wear.

I typically aim for about 36 psi also, although I dropped the rears to 35 psi last time out to minimize some of the oversteer (yes, oversteer!). It seemed to help a bit. This is still a bit higher than some have said is optimal for these tires, but I get a bit too much roll over below 35 psi. I just figured that my car was still too heavy.

Erick

Tom W

FWIW, I use MPSCs (205/255 17s) and run them at about 32/34 (+/- 2) hot. I have -2/-2.5 for camber and get pretty even wear. I did use a pyrometer at Thunderhill once and saw about a 20 °F difference across the tires (160 to 180 as I recall). The current tires (new a few months ago) have about 25 cycles on them and are still going strong with even tread wear across them. My car weighs about 2800 lbs.

I was a bit surprised to see the manufacturing code indicate that they were made in mid-2001 when I got them in May. It appears that a number of folk got tires made in 2001 about then (from TireRack).

joey bagadonuts

You might want to drop the fronts to reduce some of the understeer. Keeping the rears at an optimal pressure while dropping the fronts to a point where they'll roll over may help to balance things out.

I also heard that I'm running higher than what a lot of people think is the right number but my 3,100-lb car and pyro are telling me that 36 psi is right. I even autocrossed these tires and made the mistake of starting out at 34. A quick dash for more air got me back to the right number and made a significant difference in handling and times.

Tom,
I was curious as to why you still run the 205's up front? I thought a track junkie like yourself would definitely by reaching for the big rubber. What's up with that?

joey bagadonuts

On your questions, Tony:

1) I did not experience longer warm up periods as the tires aged.
2) With the 2nd set, I believe I had approximately 800 track miles on them when they corded.
3) I think -3 may increase inside tread wear but will still allow the tires to last longer than only -2 degrees of camber. I'll see what the pyro says.
4) On pressures, yes, I used the pyro to arrive at the 36 psi number.

Another Rennlister has suggested an alternative means of establishing correct tire pressures on the Racing and DE Forum. His advice is to calculate the difference between your cold and hot pressures and aim for variances in the 6-9 psi range. An increase >9 psi means you were underinflated at the beginning of the session; <6 psi gain means you started too high.

His approach works with my 28 cold/36 hot numbers. I was wondering what others were getting?

tonytaylor

Thanks Joey

forklift

Hey Joey,

I am thinking about going to Cups from (with actually) my RA-1s. Any new info? Are you getting better wear with the heat cycling? Have you run shaved and could you tell a difference? Shaved Toyos are much faster out of the box than full tread.

Thanks!

Jim

joey bagadonuts

Hey Erick,

Good to hear from you! Hope you're getting some serious seat time.

I haven't run shaved Cups but the original 6/32 tread depth is not at all squirmy under hard braking or cornering. And as for wear, the last set delivered ~35 heat cycles. Once again, I neglected to rotate the fronts and may have left another day's worth of use on the table.

I noticed a few pressure issues, however, during my recent track outing. I'll credit that to the fact that my driving style has changed somewhat, i.e. less braking and more cornering speed. Consequently, my pyro indicated that I'm getting a little too much heat into the center of the fronts. Next time out I'll start a little lower, i.e. 26-27 psi.

The rears have me puzzled, though. It appears I may have too much negative camber since I was unable to generate sufficient heat on the outer tread. I even dropped the left rear to 26 psi cold but that didn't help. The hot number still shot up to 36 psi but the outer tread remained relatively cool which makes me think that -3 may be overkill. Thoughts, anyone?

In terms of performance, I managed a new personal best of 2:42:1 at Road America. That's getting there and the ambient temps were only in the 50's, if that. I'll be taking a close look at temps again next week at a different track to see if the rear heat issue is still there. It's not a big deal since I usually cord the fronts first but I would hate to think I'm giving up any grip.

Additionally, one of the racers on the Race & DE board (Chris Cervelli) tested the Cups head-to-head with the Hoosiers a few months back and concluded that they are equally fast. He did cite that the Cups offer relatively small slip angles and can't be pushed in quite the same fashion as the Hoosiers. That may explain why so many people are convinced that they are faster on the Hoosiers and that the Cups take forever to warm up--that's how they're supposed to feel!

Finally, last Fall I saw a pretty impressive display of RA-1 prowess. I was again at Road America and one of my friends was able to get by me in his Toyo-clad S2000. Oh yeah, he's definitely talented but I was equally impressed by the amount of grip delivered by his shaved RA-1's. If I wasn't so averse to change, I would give them a shot especially since they last twice as long as the Cups, cost a few hundred dollars less and offer comparable performance.

I'm not sure you'll see a dramatic difference in lap times with the Cups but they're certainly a great tire. Their best quality, IMO, is that they don't get greasy or overheated during a long, hot session--they're extremely consistent. But don't forget, they suck in the rain (even with AWD) so they may not be as versatile as the Toyo's.

Hope that helps. Questions?

burgass

Thanks Joey!

forklift

Perfect, thanks Joey.

I am a bit reluctant to change from my Toyo's but I hear they are worth 1-1.5 seconds, and I would like that extra time. I love my Toyo's, very, very predictable at the limit (breakaway characteristics) and do last forever. I got something like 80 heat cycles out of the last set, although I am driving them much harder (faster) now, so not sure how much longer the ones I have now will last. I am thinking about making Cups my spring/summer tire and the Toyo's the fall/winter tires for the warm up reasons and the fact that Cups apparently take longer to overheat. $ is tight while I am waiting for my house to be built, so I guess I will be going w/o a rain tire for a while. My rain tires will be full tread Toyos when I do get some as I have run those and the 0-32s in the rain and like the Toyos much better.

I think I got around 32 track days last year and have about 40 or so scheduled for this year. With that many days I might be switching back to Toyo's if the times aren't that different. I still have some wear on mine anyway, so they will stay mounted and ready to go. They work fine in the wet as long as there are no puddles.

Thanks and congrats on racing! I will just be driving and instructing DEs for a while. Maybe racing in '07. I will report back on the Cups vs. the Toyo's after my 5/13-15 DE.

Thanks,

Jim

Bill Gregory

Joey,

Interesting that you arrived at 36 psi in the rears through tire temps. You probably know that Michelin recommends rear pressures of 32-35 psi for 964's. Like others, I tend to run in the 32-34 give or take range, as I've found above 36 that the MPSC's don't stick as well. Michelin recommends 26-28 psi in front for 205 tires, and says that lower pressures are 'favorable'. Still feels odd starting off with like 22-24 psi cold in front.

On heat cycling, Michelin says that heat cycle tires come up to pressure quicker, which supports your observation on quicker stick, and on some cars they see a marginal improvement in lap times and tire wear. They add that the improvement is not always obvious.

Camber: Michelin says to target negative 1.5 to 3 degrees with a max of 4 degrees. They caution "Do not get too crazy here". FWIW, I run around -2.5 and have even wear.

Tire temps: MPSC's like to be hot, with recommended temps in the 160 to 220 degree range.

forklift

Well just when I thought I was sold on trying out the Cups, Paul (ex Trans Am racer) from Radial Tire talked me out of them, so I will stick with the Toyo's for a while. He said that almost everyone he sold Cups to in 2003/early 04 either progressed to Hoosiers, or went back to using the RA-1s. I do love that tire, I was just looking for another second.

Jim

Tom W

I'm on my 3rd or 4th set of MPSCs (I use the 205/255 sizes). I recently bought a set of Toyo RA-1s for one of my extra wheel sets, planning to use them as rain tires. In dry conditions, I don't think the RA-1s stick anywhere near as well as MPSCs, but I haven't used them enough to really get comfortable with pressures with them (what do you folk use?). I run the MPSCs at about 32/34 f/r. Based on Bill's comment, I may try a little less pressure in the front (but I'm going to check my "care and feeding" article again, I thought it recommended 32/34 for 17" tires). I used to run -2.0/-2.5 for camber and was getting too much wear on the outer edges. I've since switched to -3.1/-2.8 and will see how the wear on the cups goes.