Finally, spring is upon us and I will soon order my r-compound tires for my Grand Sport. This will be my first time ever with such tires; exciting!

I already have a set of brand new OEM Z06 wheels to use for track duty. Anyhow, for a long time I was sure I'd order Hoosier R6s, but I think I changed my mind about this:

R6 seems to provide one of the best-in-class traction (if not the best) for our cars. I was planning to rent a trailer and tow my car to every road-course track day I'd attend. The problem with this solution is:

(1) Hoosiers suffer greatly from heat cycling. In other words, they can take only so many heat cycles before their compound gets harder and at that point, they lose their edge. A highway trip, unfortunately, counts as such a cycle if not more than one (depending on rest stops, distance, etc.).

(2) I indeed plan to tow my car to the far-away tracks, but my local track, Pacific Raceways, is only 35 minutes away and I don't want to rent a trailer and tow my car for that short of a distance.

Enter Michelin Pilot sport Cup (Not the ZR1-spec ZP version that's only available in 19"/20" wheel sizes):
If I understand correctly, these tires do NOT suffer from heat cycling! Michelin explicitly states that they should perform just as good until they are worn out even through many heat cycles (http://www.tirerack.com/tires/tirete...nd_Feeding.pdf). On the top of that, they are also supposed to last longer than the Hoosiers and provide almost just as much traction. Guys, if they indeed do not suffer from heat cycling, they are the ultimate street tire!

Here is what I am wondering:
(1) I am planning to get 295/30/18 (25.2" OD vs. 25.6" OD stock) and 345/30/19 (27.2" OD vs. 26.7" OD stock). Would these sizes rub on the wheel wells and/or trigger stability control issues? The diameter gap between front and rear widens from 1.1" stock to 2".

(2) If Michelin's claim of consistent performance throughout the tire life is true, why aren't you all supercharged Corvette owners, especially those who live in south, using these tires for the street? After all, someone who can afford a forced-induction upgrade should hopefully also afford to get the sticky tires the car deserves and replace them every 5K?

 

Sport cups are great the two reasons they are not used much are that they are not as good as a true race tire (hoosier etal) but they are a very good tire for your intended use I have used them in the past

 

Cool, thanks for your input. Once I realized they don't lose traction in time as other hardcore race tires do, I was just amazed that it's not used commonly by those who need every bit of traction, like those with the forced induction engines.

I'll order a set shortly

 

Here is what I am wondering:
(1) I am planning to get 295/30/18 (25.2" OD vs. 25.6" OD stock) and 345/30/19 (27.2" OD vs. 26.7" OD stock). Would these sizes rub on the wheel wells and/or trigger stability control issues? The diameter gap between front and rear widens from 1.5" stock to 2".


Would the difference in diameter actually be from 1.1" stock to 2.0"?
I also have been wondering how far this ratio can be pushed before causing problems.

 

Oops, yeah I had a typo: it's actually 1.1". I'll also fix the original post.

So, to reiterate: does anyone know if we run into stability control / ABS issues if the OD difference jumps to 2"? What's the limit?

 

I run those sizes on Nitto Invos every day. No active handling or drag control active issues. When I first put them on, the fronts rubbed a little at full lock on the front top of the gurney lip backing out of my driveway which has a large dip. It wore down the lip just slightly (can't notice it) and hasn't done it in a long time. My car is also slammed really low, if you aren't so low it shouldn't rub at all.

 

Make sure you test it out well before pushing it at the track. I went from 1.2 to .9 and TC would kick in at around 100mph.

 

I went 180 mph + 3 times with the size tires the OP is considering at the Miami Mile event, no active handling issues. I turned off traction control, which is why you see the traction light on.

 

You also need to take into account that, during a session, after 4-5 laps the Hoosier's will continue turning consistent lap times while the Michelin’s will start to decrease in traction.

 

I forgot in one of my sessions. Hit the front straight and TC kicked in. Live and learn.

 

Joe
Are you running the 295/35/18 on front, or 295/30/18 as OP listed?
The 295/35/18 I believe is 26.02" diam which would keep the ratio at 1.1" different front to rear if I'm not mistaken.
Thanks
Jeff
Oh, Beautiful car BTW

 

Same here with my Z51 C6. With 275/35/18 front and 305/30/19 PS2's the TC will kick in around 90 mph on hard acceleration at the track. I now have to drive with TC off to avoid this.

Aiming for 265/305 combo next time.

 

So are you guys saying 295/30/18 and 345/30/19 combo will cause issues with traction control? I just ordered a set from Tire Rack, but I guess I can still cancel it if it will cause issues.

 

wait...doesn't the z06 come with the option to add the cup tires? why not just use those?

(or is it only on the zo6 carbon which uses zr1 brakes so im assuming zr1 wheel/tire sizes?)

 

Those cup tires indeed only come with that Z07 package, and require 19/20 wheels.

 

OP I'm sorry, mine are 295/35/18, I didn't realize you were wanting 295/30/18. I missed this looking on my phone and focused only on the 295 size marker. My sizes keep stock ratio, I'm afraid yours won't and will cause active handling issues.

I wonder if anyone in the Road Race section is using them? They would know for sure.

 

Unfortunately, I think you're right: there are no good sizes for MPSC tires that would not trigger an error. If only they had 35 profile front tires. At this point all I can see as an option is again the Hoosier R6.

I think I'll get Hoosier R6 275/35 (25.5" vs. 25.6" stock) or 295/30 (25.2" vs. 25.6" stock) fronts and 345/30 rears as a set. Hoosier's 325s and 345s have the same OD (both 26.8" vs. 26.7" stock), so I guess you can run 345s with no TC issues.

 

Ozer, give me a call and we can discuss your options

I will put your order on hold until we talk ...

 

Ozer,

What about the tire width for the rears? Will 345's fit without hitting the fender? The 325's seem mighty close.

 

Now this I can speak to....see pic above. My 345/30/19's never hit the fenders - I'm using stock z06 size rims.