Gearhead Jim

The car is a 2009 Coupe w/Z51.

I'm on my second set of Michelin PS2 runflats, and they've been an excellent tire for both touring and pushing the twisties.

Recently, everyone has been raving about the Super Sport runflats in my same sizes. Cheaper, better tread life, and more comfortable. And many claim they have more grip.
But...

An experienced autocrosser who is familiar with both tires, says the base/Z51 PS2 runflats still have a bit more grip than the SS runflats in that size. We didn't talk about the non-runflat SS, nor about the GS/Z06 sizes.

It seems that the term "Super Sport" is coming to identify a whole group of Michelin tires, that are different in more ways than just size. Kinda like the Goodyear "Eagle" name.

My acquaintance thinks the base C7 (and fit the C6) Super Sports have more emphasis on the comfort/life/price factors, than on max grip. Whereas the C7 Z51 and C6 GS/Z06 Super Sports are oriented toward max performance. Some of the publicity info from GM when the C7 was first introduced, talked about the C7 Z51 tires having certain design features that were not mentioned on the base C7 tires, which supports the theory.

So, does anyone here have experience in comparing the PS2 runflats and Super Sport runflats, in the base C6/C7 sizes?
Enquiring Minds Want to Know...

Thanks.

Bad Karma

I can't comment on the runflats. But for the standard variety going from S2 to Super Sports, I didn't feel like I lost any grip, and so far the Super sports are wearing very well. Based on my C5Z.

FAUEE

PS2s are the "bread and butter" Michelin sports tires. When BMW, Mercedes, Corvette, etc. want an OEM Michelin, they typically get PS2s because they can be "customized" to the parameters wanted.

The PSS is a performance tire, pure and simple. They will have more grip than the PS2, and be second only to the Pilot Sport Cup in the standard Michelin lineup.

Pilot Super Sport is a specific model of tire. Pilot Sport PS2 is as well, but they tend to be more customized by the automakers. I think your best bet is going to be to send an email to Michelin and ask them.

I will say this - I have PSS on my Grand Sport, and my father has them on his Porsche 993. They grip like holy hell and actually last a good bit of time. They're fairly quiet and comfortable, but they're certainly not a touring tire. They are performance tires, pure and simple. If you are looking for more of a daily driver tire that would be comfortable to commute in, they are not the tire for you.

Gearhead Jim

Since we've been happy with wearing out two sets of the PS2 runflats on our 2009 coupe, I think that the comfort of the SS would be fine for us.
But I'm interested in the grip issue. It would be nice to have a G-meter comparison; same car/pavement/driver, on the same day.

Gearhead Jim

Perhaps the best info on the base SS runflats would come from how they perform on a base C7. In steady state cornering, the C7 suspension probably doesn't perform much different from the C6, so the tires would be the main variable.

"Official" GM cornering numbers for the C6 Z51 on the factory Supercar tires, shown as .98 and .99, PS2 runflats seem about the same.

"Official" GM cornering numbers for the C7 Z51 on the factory PSS tires, lower profile than the base car, shown as 1.03
With the lower profile tires and slightly better (?) suspension, I would have expected a bigger improvement.
I can't find any GM cornering numbers for the C7 base, which would be the proper comparison. Does anyone have them?

Two cautions:
GM performance numbers are sometimes written by the advertising department, so I don't take them as gospel.
Steady state cornering is only one component of handling. But it's a good start.

Lawdogg

I run SS on my BMW 335i daily driver. Great commuter tire in addition to being a great performance tire.

mikeCsix

Jim,

I ran the PSS's on my GS for the first time this year. The first issue I ran into was tire pressures. Michelin's recommendations were too high in my opinion and had a deleterious effect on handling. I slowly worked the pressures down until I had a workable formula. Generalities, I know.

I can tell you at the right pressures, I was seeing 1.18g's steady state cornering. Granted, these are on a GS so YMMV. In comparison to the GY Supercars (IMHO not a bad tire at all when properly warmed and at the correct inflation pressures), I saw a max of 1.05g's. Yep, there was more available, I just leave some for safety. I think I could get to 1.2, maybe a bit more.

What you haven't mentioned is your intent with these tires? Are you planning some track days where you want to generate max g's? If it were me, I would stay with the RF Michelins unless there is a tire wear issue you are trying to get around. The RF's are a lot of piece of mind for long road trips. As far as noise and general street handling, I don't notice much difference between the brands and tires. Noise is about the same the the Mich's are a little quieter. The PSS's tend to not follow the lines in the road as much as the GY's, but they all do it to some degree or another. Let's face it, the steering is sensitive in these cars, they are high powered sports cars with razor sharp steering and for me, its to be expected. If I wanted a Cadillac, I would have bought one! After a session on a road race track, there are enough marbles stuck to the tread they sound like snow tires anyway and take a while to wear off.

In summary, the PSS's are a bit less expensive, grip well at levels I notice on the track and may last longer than the GoodYear's.

HTH, Mike

Gearhead Jim

Mike-
For me, the only choices right now are the Michelin PS2 runflats or SS runflats.

The car is used as a daily driver, long distance road tripper, and autocrosser.

No single tire will excel at all of those uses, but our existing PS2 runflats have served us well.

I'm going to stay with runflats, here's my story:

https://www.corvetteforum.com/forums...flat-tire.html

strano@stranoparts.com

There are definitely specific tires under the overall headings of PS2 and Pilot Super Sports. I.E. they aren't all the same.

The C7 has bespoke PSS's, not run of the mill PSS's. And make no mistake they are awesome. PSS's in general aren't bad, but having run both on C6's PSS's on a Z06 and PS2's on a Grand Sport, and though they aren't the same cars I know both cars very well having owned and won many National events in both (of note the PSS's on the C6Z were NOT run-flats). The PS2 ZP's were faster than the PSS's.

Does that help?

Gearhead Jim

That does help, and it sounds like you and my acquaintance both agree- the Corvette PSS are great all-around tires, but not quite as sticky as the PS2 if you want absolute maximum grip.

Thanks.

mikeCsix

Jim,

In GS/Z06 sizes, the Pilot Super Sports are non RF only (too bad!!)

I'm surprised to see Stan's comments regarding the PS2 ZP's being faster than the PSS's, was that autocross or road course? How much grip was available? Any hard numbers or lap times?

My previous PS2 ZP's were on a Z51 equipped 2008 I used on road course events. They worked well and inspired confidence in the turns, but can't make comparisons to the GS and don't have hard numbers for them.

strano@stranoparts.com

It's Sam, not Stan.

It was an autocross on a site I run a lot. It was better than .5 on 30 seconds difference. Not the slickest place around, not the stickiest. How much grip was available? How do I answer that?

mikeCsix

OOPS! My bad, Sorry Sam! Thanks for the reply and insights.

"How much grip was available?" Somewhat subjective, I was thinking as measured by the g-meter and a guess as to how much further the tire could be pushed. Much easier on a road course, the autocross courses are so quick I'm sure there isn't time to glance at a hud, I know on a lot of turns on a road course there isn't time!

It has been my experience for street tires, the Michelin's do really well.

The Porsche guys say not to use Run Flats on road courses, their reasoning is they don't generate as much grip as the non Run Flats. I don't have enough experience to be able to comment.

But back to Jim's question, how hard do you want to push the car, especially on public roads? I don't drive much over 5/10's on the street and save the rest for track days. In that regard, just about any of the tires discussed would work well, even the much maligned GoodYear Supercars.

LFZ

I have tracked a C6Z06 on OE 19/20 PS2 ZP (runflats) as well as the PSS (non runflat) in stock 18/19 sizes, and even the 1 up 285/345 sizes. IMO and from my experience, I felt the PS2 was every bit as grippy and handled just as well as the PSSs. On the street, there is no notable difference, but like the above poster mentioned, I had faster laps on the PS2s. *I would say it has a lot to do with the specific development of the tire as the PS2 ZP was made for the C6 Corvette.

strano@stranoparts.com

no problem

I don't know how you guys ever look at the HUD anyway, drives me nuts even driving down the road. And I certainly woudln't dare look at it if I was pulling enough g to matter what it read.

Michelin's are super nice tires no doubt but they aren't all the same. Run Flats often don't make as much grip as non-RF's but that's a universal truth. Most RF's are OEM and wear is a concern there. But the flip side is that sometimes a stiffer tire works better. not always again, I'm certainly not a fan of the F1 Supercars in EMT form (only slightly less hating of them in non EMT form).

DigitalWidgets

I'm not an expert racer or anything like that (yet!), but I'll share my "real world" input:

I've gone through 2 sets of PS2 (ZPs) and 2 sets of PSS (plus the OEM GYs originally), so I've had a pretty good sample set. I'm burning through them because I've become an avid autocrosser over the last 2 years. I can only share this: With my PS2's I consistently PAX'd at the lower half of the pack. Since I switched to PSS's (albeit non-RFs in my situation), I've finished consistently in the top 1/3 of at our local events (of typically about 200 participants)...some of that is that my driving skills are improving (slowly, but I'm getting better each event)...but there was a sudden jump from "out of the running" to "chasing the leaders" when I switched to the PSS's.

To be fair, the PSS's probably only got me a portion of that improvement. I also found a performance oriented alignment shop that did a corner balance and a fairly aggressive alignment. They did it all while I actually sat in the car (i.e. taking my weight into account) and they lowered the high side of the car to get the balance (i.e. my weight lowered the driver's side a bit, so they lowered the other side to balance). This also made another world of difference in my autocrossing performance. It also made the street performance a heck of a lot more fun as well. Of course the air dam scrapping is much worse than it ever was with that little bit of lowering.

I'd definitely give the PSS's a try if you're interested in performance...and while your at it, think about a bit more aggressive alignment. In my situation I'm wearing out the tires much faster by autocrossing than the inside wear daily driving on the street with the negative camber and a bit of toe-in in the back.

Not a lot of choices for GS stock rim sizes and Street class tires...I might be trying something else on the fronts next time (my fronts wear out much faster than the backs with autocrossing)....but not sure how I feel about a mis-matched fronts/rears at this point. But as I've said...I'm certainly no expert!

strano@stranoparts.com

I think you are way underestimating the alignment and your experience level increasing. Those are HUGE. Also I assume the PS2's weren't new but had some heat cycles when you started with them? vs. a fresh set of whatevers. And you are comparing run-flats and non-run-flats which is pretty apples and oranges.

05dsom

night and day

that being said I will replace my (run flat) PS 2's with PSS and my 2nd set of PS cup with cup 2's when they become available.

DigitalWidgets

I can't disagree with your comments (except that the last PS2's were a new set).

The alignment changed everything....it was like getting a new car.

And you're right, experience is starting to pay some dividends. The minor mistakes are still a work in progress, but the big mistakes are getting fewer and fewer. Learning to manage temperature and pressure is also a factor.

I'm sure RF vs. Non-RF is a factor as well...the non-RFs are definitely much quieter for daily driving. That being said, throughout the life of the PS2's, with my A6 and the paddles, I could easily break the back tires into spinning just about anytime in 1st and 2nd....with the PSS's it's much more difficult.

I'm trying to stay in a street tire class, and there just doesn't seem to be a whole lot of decent options to get maximum performance for GS rim sizes (at least I can't seem to find any).

But as I've said, I'm no expert...I've had 2 sets of each of the tires in question....these are just my observations. YMMV!

el es tu

Supersport is the replacement for the ps2. Its a better tire, however, there are much higher perfoming tires for the base c6.

Bridgestone RE11 and Kumho XS are 200 treadwear and have more grip than the supersports. The bridgestones are better in the wet and cold while the kumhos are a slight bit stickier on dry pavement.

Pirelli makes a sub 100 treadwear tire (Trofeo R). This tire offers even more grip than the bridgestones or kumhos.

All the above tires are available in the 245/40R18 and 285/35R19 setup.