X25

My car comes with the cup wheels, which severely limits my choices when it comes to replacing the tires. I would love to replace my tires with other ZP/run-flat tires for the huge safety benefit they provide at high speed, not to mention the convenience if they ever go flat. I have been hoping for Michelin to announce the new PSS ZP tires for C7 sizes along with the C6 Z06/ZR1 sizes, but have not heard anything about it, and starting to think it might not happen. Below is my backup plan:

OEM sizes:

• Front:P285/30ZR19
  Tread-width: N/A
  Diameter: 25.8"
  Weight: 31 lbs
• Rear:P335/25ZR20
  Tread-width: 13.5"
  Diameter: 26.6"
  Weight: 35 lbs
• Diameter difference = 0.8"

My proposed PSS sizes:

• Front:P275/30ZR19
  Tread-width: 10.2"
  Diameter: 25.6"
  Weight: 26 lbs
• Rear:P325/25ZR20
  Tread-width: 13.1"
  Diameter: 26.3"
  Weight: 31 lbs
• Diameter difference = 0.7"
• Odometer/speedometer would read %0.76 more (negligible). E.g. @80.00 MPH, it would read 80.61 MPH.

My remarks:

• The staggered diameter difference is almost the same: the original 0.8" vs. 0.7". This hopefully ensures stability control, traction control, PTM, magnetic suspension, etc. all work at their optimum performance.
• The outer diameter of rear tire is also almost negligible, leading to very low error at speedometer.
• The PSS tires are substantially lighter (18 lbs total!!).
• This set-up loses a tiny bit of tread width, but keeps the proportions almost identical to stock setup, which I think is very important.
• I'd love to use the ZP version of PSS tires (ZP also adds less weight to PSS tires than it does to PS2 tires due to new design as far as I understand), but until we get it, regular PSS is all I have if I were to go with PSS tires.
• Price: $1478 shipped to my home for PSS v.s. $2100 shipped to my home for the OEM PS2 tires.
• As you all know, PSS tires also last much longer vs. PS2 tires with their unusual 300 tread-wear rating. They are also claimed by the manufacturer to last 50% longer at the track.

What do you guys think?

ibleedgreen

That would be great. I would like the option of the 285/345 combo as well.

I would like to see the Nitto NT05R drag radial available in a 345/25-20 as well. And I think we may see that sooner than the Michelin.

LFZ

I went through this same thing a few months ago. With the shortened height of the SS tires, I'd be afraid of any sort of compromise with those sizes. I'd stick with PS2s in the correct sizes, and I know I'll probably get flamed for this, but I felt that my PS2 ZPs in 19/20 proper sizes, were every bit as good, if not better than PSS equipped Z06 I drove in 18/19 sizes.

WhiteDiamond

I won't flame that one. I am getting ready to step up to some satin black cups in the 19/20 for my Z and asked for some feedback on tires. From what I got, the PS2 ZP is a great tire and possibly a tad quieter in the car than the PSSs. It sounds like grip is identical and any difference may just be personal confidence related.

Lawdogg

I went with Nitto Invos on my cup wheels for street use. My car is set up for track days on slicks. Coilovers, bushings, sways, aero, -3.2 degrees of front camber, etc. Even so, the Invos are limited in dry grip. Wet is ok, but they are essentially a weak dry performance tire. Stick with PS2s. I wish I had.

X25

I also did try PSS tires in 18"/19" stock sizes on Grand Sport, and was not blown away by the performance. I also tried cup tires in 295/345 18"/19" sizes, and found that the difference in performance was easily quantifiable during hard braking since cup tires let me brake much harder and much later; a difference I could easily measure.

Back to today with the '13 Z06, I find myself looking for more traction in the braking zones, and I do not get enough confidence to brake harder and more into the braking zones with the PS2 tires. This is a different car after all, and perhaps I will feel the same even after going with the PSS tires, but there is no easy way to find out other than actually trying the tire.

The drop in the profile width might actually be a big issue as you guys stated since the car does not come with much profile width to start with in original 19"/20" sizes, not to mention the lack of ZP, which stiffens the sidewalls further with additional support on PS2. I am not sure about this one, either

What I read from responses make me want to switch to the cup ZP tires available in OEM sizes. I am OK with the trade-off of the shortened life, but I presume they would be a handful when it rains here in Seattle area.

X25

I ordered the tires I have proposed just now, and will get them on May 1st. I will put them to test shortly after. If anyone would like PS2 take-offs, please let me know. I will measure the tread depth once they're unmounted.

ATC399

Lets us know the results....

X25

I did get the tires installed today. My car doesn't appear to scrape in any one of those bumps where I know it gets close to, so it doesn't appear to be riding significantly lower due to lower profile. The comfort level also appears to be similar, so no issues there, either.

I will have an opportunity to test capabilities of these tires over the weekend. I will keep you posted

ATC399

Thanks for the update...

LFZ

Please get some pics posted as well...I'd love to see how they look.

ATC399

X25

Alright I rode to work (bicycle), but will take pics when I get back

LFZ

Get pics of bike too.

X25

325/25/20 Michelin super sport tires on cup wheels. It doesn't look like it has much less sidewall compared to the PS2s. Looking forward to driving/testing them comprehensively over the weekend

ibleedgreen

very curious, looks to me like they need to be wider.

LFZ

Those look very thin and stretched! Any more shots??

intheboost

Looking forward to your review and more pics.

X25

PS2s also looked pretty much the same. I'll try to find pics.

LFZ

No way bro...PS2s look way beefier. As long as the performance is there...that's all that matters..but I'm a visual guy also so that means a lot to me..