nhpln

I have a C6 Z06 but have the Michelin PS2 ZP tires on my car. I figure I'd get more responses in this forum since the PS2 ZPs are standard on the ZR1.

Has anyone run these tires "inside-out"? By that I mean that the edge normally marked on the tire to be the outside is actually on the inside? I track my car and have found that the outside edge gets worn heavily and so I want to flip the tires on the wheels to even out the wear. I am aware of the fact that the outside edge is designed for dry grip and has larger shoulder blocks to aid in stability while the inside edge is designed for wet grip and has smaller shoulder blocks.

My camber settings are -1.5 deg front and -1.3 deg rear, so I'm pretty sure that not enough negative camber is not the issue.

If anyone has done this, let me know if there was a severe impact to handling.

range96

The tire construction is asymmetrical. I've seen a cross section cut out piece and one side is really firm (to support the car with ZP), the other is much softer.

I doubt anyone here is adventurous enough to try. If you try it let us know how it feels. If you flip all 4 it may work, I don't know.

I flip Hoosiers, they are symmetrical.

vetteship

I would not do it.

jrummi

Ya, I've seen this too. The ZP thing is only on the inside sidewall, the outside is softer. Flipping would probably work fine for just cruising around but since we aren't talking about a cheap ford piinto I'm sure you like to do more than just cruise around. I wouldn't flip them.

range96

Where is your daring side? Common, try it (and let us know). It may be the next secret trick for the track.

I'll stick to my Hoosiers, though. OK, maybe I'll try the MPSC's once they are available.

peterpiper

I do... but you already knew that

No problem... I'm able to get up to 1.0 - 1.1 g sustained on chuckwalla... 2:04.xxx lap times in the Z06
The asymetrical firmness works to your advantage with not enough -camber when they're inside out. I'm running at about -1.4 front -1.1 back camber.

The only issue is rain, but hey, this is socal.. it NEVER rains.

Don't know what happens on the track if you get a sudden flat.

-pp

range96

Are you saying you run them inside out and get those results? On all 4? What are your numbers with outside on the outside for comparisons?

peterpiper

It was the first time i had PS2s at chuckwalla. All 4 tires were inside out.

for comparison, on the spring mountain school track, I'm able to get 1.0-1.1 with the tires mounted correctly, lap time 1:51.3. Same setup. If I get some time this weekend, I'll see if I can get a video of the laps with the g-meter overlays.

-pp

range96

Putting the firmer side on the outside should help to prevent rolling over the sidewall (better wear?), but will likely be detrimental to handling. Caveat, I'm guessing here, would like to see real data.

nhpln

Thanks Peter. That's a great time for Chuckwalla! I think I'll go ahead and get the tires flipped this weekend. We'll see if the installer looks at me like I'm from Mars when I tell him to flip them.

peterpiper

How did it go, Mr. Martian?

Sorry, everyone, I haven't had much time over the last couple weeks to get the comparison videos out, but I got half of it out... Here's a video showing the performance of inside-out tires to keep the thread going. This is my fastest session which shows a larger G meter at the top. e v e n t u a l l y I'll get a video with the correctly mounted tire. (these videos take a lot of time to process to get to this point)

http://www.youtube.com/watch?v=rX4QrgEE-zk

go to lap 3 for best use of tires

(@nhpln: have fun at Laguna Seca-- I'm in the process of changing my hub bearings)

-pp

peterpiper

Another point to note: I drove an identical car with Kumo Ecsta XS tires-- they felt MUCH softer than these PS2s inside-out. FWIW. So even though the inside wall is on the outside, the PS2s are much stiffer than non runflat tires with the outside on the outside. -pp

Bottom line... I still prefer the PS2s, but there is a design flaw with the outside "corner" of the tire at their recommended PSI for track driving. In order to stop the abnormal wear on the outside, you have to add more PSI--which then abnormally wears the middle of the tire.

Michelin should look at this problem the other way around---test out some inside-out tires and see why the wear is better than mounted correctly. (i'd be happy to help test ) THEN they could modify the tread so it works well in the rain. -pp

nhpln

I'm back from Laguna Seca after running with all four PS2 ZPs inside-out. My best time there last year (with the tires mounted correctly) was 1:43.9. I was able to do a 1:42.1 this time around with the tires inside-out. Some of the improvement likely came from familiarity with the course, but I also had to shift into a higher gear by the sound meter to not blow the sound limit so that didn't help times. It seems fair to say that grip was no worse even with the wet half of the tire on the outside. I couldn't detect any difference in stability. Ambient temperatures were about the same as last year.

The tires got up to 38 PSI hot. The wear on the edges is acceptable and much better than when the tires were mounted correctly. However, as Peter mentioned, the center section got chewed up and looks pretty ragged. I'll try to post a pic tonight.

I usually run Nitto NT-05s on the track and prefer the PS2 ZPs by a good margin. The steering response and sidewalls are much stiffer as is to be expected from a runflat. I just wish they had better wear characteristics.

WB6HRO

As I understand it the PS-2 and the new Super Sport tires have two different rubber compounds. The other edge compound was developed from endurance racing aka Le Mans so they could double stint tires. The center and inner edge is more for rain and lightly loaded grip.

Running the outer edge on the inside will increase tire wear. Typically the tire pressures go up 4 to 6 pounds on the track.

nhpln

Here's a couple pics. Center section tapers pretty badly.

range96

Based on your pictures you would benefit from a little more negative camber and taking out some air.