Hello all,

I just had new tires put on my car. It had the Corsas that originally came w/ the car and I replaced them w/ the Michelin PS2s. I was expecting good things based on recommendations of others and what I’ve read on forums such as this, etc. My initial impression is not good:

1) On center turn-in response at speed (~60-70mph) is poor. Unlike the Corsas, response is slow and vague. I’ve felt better response from a heavy sedan.

2) Mid-turn, the car doesn’t want to take a set and the steering wheel feels lighter than normal and even “springy” for lack of a better description. Also, small bumps seem to unsettle the car more so than usual in the turns.
With so many tire recommendations pointing to the PS2s, I’m not jumping to any conclusions about the tires being the problem. I do have some questions:

1) Do the PS2s like a different setup from the Corsas? (Toe, Camber, etc.) Seems unlikely.

2) I had the tires filled /w Nitrogen. Should the cold static pressures be adjusted from what the manufacturer recommends to account for the fact that the tire pressures will not rise as much with temp as with an air fill?

3) Did I make a bad call trading in the Corsas for PS2s?

Thanks,

-Roland.

 

Quote:

Originally Posted by rja

Hello all,

All this could be attributed to several different things. Probably a stupid question but did you have the tires balanced properly?

Also, i'm not sure how PS2's are but the Sport Cups were infamous for being greasy right off the bat. How many miles are on your PS2's? And i believe the PS2's do have a softer side wall.

Quote:

Originally Posted by rja

1) Do the PS2s like a different setup from the Corsas? (Toe, Camber, etc.) Seems unlikely.

Yes but it's some what backwards. You'll see better results with more camber on R-Comp. A camber set up for R-Comps shouldnt result in less performance with the PS2's just worse tire wear. Although you're some what comparing apples and oranges here.

Quote:

Originally Posted by rja

2) I had the tires filled /w Nitrogen. Should the cold static pressures be adjusted from what the manufacturer recommends to account for the fact that the tire pressures will not rise as much with temp as with an air fill?

Yes, i found that the PS2's definitely need a little heat in them to function properly.

Quote:

Originally Posted by rja

3) Did I make a bad call trading in the Corsas for PS2s?

Depends on your usage... Do you see much rain? Do you track much?

 

The tires are new (less than 50 miles) -- they were balanced. I realize it takes some miles to scrub in new tires, but in my experience the change is not drastic w/ street tires. Believe it or not, this is my first time ever w/ Performance Michelins tires (I've always gone w/ Pole Positions in the past for street cars, Toyos and Hoosiers for the racecar) ... so if it's just that the Michelins are notoriously greasy at first then no big deal -- I just drive it off.

I do see rain (live in Seattle), I don't track the car very much.

Thanks for the reply,

 

Ya, hopefully that's the case. And i'm sure you're already aware but going from an R-comp to a street tire you're definitely going to see a drop in performance. Good luck!

 

from Corsa to PS2 is down-grading. only do it if u want to get more tread life. otherwise not worth it. Corsa is much predictable around the bends imo.

 

i agree with arling, the ps2 is a complete downgrade from the corsa's. but also keep in mind that the ps2's probably need a good 500 - 1000 mile break in period. but.. even so, it will never perform as well as the corsa. i would only put corsa's or cup tires back on my gt3 when i need to change tires

 

You are talking about track performance, right? If street only, then whether Corsa, MPSC, or PS2, you are never using anything close to the capacity of the tire. I think every tire has it's own feel and you just aren't familiar with the PS2 yet and 50 miles is clearly not enough - you are barely getting the release agent off of the tread.

I've got probably 60k miles on PS2s on street, dry track, cold track (26-40 degrees), very wet track, One Lap, etc. I've also driven considerable miles on "real" MPSC and the "hybrid" 19" that come OEM on newer Porsches (debated elsewhere, these are really PS2s in disguise). I have a set of Corsas waiting to go on, so I don't have any experience with that tire.

In general, even the Corsa isn't a true R-comp as it's a certain formula to work in wet and cold, else Porsche would never have put it on as OEM. Just to give you an idea of how good PS2s can be - I owned my 07 GT3 a total of 2 days when I went to Watkins Glen. I was turning 2:15s and better with the car bone stock on a set of new PS2s I had the dealer put on. Tires had about 800 miles on them (500 to get home from dealer, 300 to get to The Glen). PS2s are pretty amazing once you are used to them and they are the "do everything" tire - cold, rain, dry... Long wearing...

As to nitrogen, a dealer put it in my 997S when I bought it and I monitored change at the track and it wasn't worth bothering with. I think it reduced my PSI spike from 10-12 by maybe 2 lbs. Then to put air back in after the track, I would have had to go back to the dealer. Just not worth bothering with, unless maybe you are racing for money.

Also, what pressures are you using with the PS2? It's different than the PSC or Corsa. 33/39 cold is recommended for PS2 on the street and that's what I used with both my 997S and now my GT3 on the street. Track I found 34/35 hot to be good.

 

like others said, give it 500-1000 miles for the tires to get heat cycled and the compounds to get more stiffer...

more info here,
http://www.unofficialbmw.com/all/tir...ing_tires.html

 

I don't think you get any benefit from heat cycling street tires, and even some track tires (ie: RA1s, 19" MPSC, etc.). Only true racing compound tires (well, some DOT tires too like "real" MPSC) need heat cycling.

When I heat cycle R-comps, I do it myself while I also bed in my track pads. Get them to proper temperature, then let them sit for 48 hours (24 is probably enough).

Tires like PS2 are formulated such that they don't benefit from heat cycling. But they do need to be worn-in mostly to get rid of the "stuff" they spray in the mold to allow the tire to release.

 

RJA I did something similar. I went from PSCups to PS2s. There is a breakin AND there is a downgrade. The upside is I got 5K miles on the Cups and the wear rating on the PS2s is twice as much. I also took 10lbs off each corner by going go Fikses WHeels so my performance went up and down. I changed too may variables.
The thing you have to decide is do you want a High performance tire that last longer than that hi performance tire that just feels great all the time but lasts half as long.

 

I would call the shop that you bought them from, if you aren't happy then maybe they will swap them out for MSPC or Corsa.

I deal with a shop that wants you to be happy, tires wear out. Happy customer is a repeat customer.

 

*Ding!* I believe Ron has hit the nail on the head. The mold release compound takes a while (but not 1,000 miles) to get worn off.

They'll get better in a little while - but not obviously up to R or pseudo R levels.

 

Going from an R-compound to a street tire will always be a downgrade for sure in all aspects except for rain and wear. If you only drive the car in good weather I'd definitely go back to Corsa's, MSPC, Yoko AD048, or R888 (which is what I run)

 

Lots of guys are starting to like the R888s I think thats my next tire to trye

 

I have a set of R888s Held up well on a lapping day and were pretty decent at an auto-x as well. I'd recommend them.

Only downside so far - they are pretty noisy but for a streetable R (I wanted a tire I could drive to events on ) they are excellent.