Rinaldo Catria

Jim... could you give us an “educated guess” what time you would run Road America in the ZR1? Porsche just ran the GT2 RS there and set a record.

Jim Mero

The last time I was at Road America was in the mid 80's in a go kart. So probably not.

I'm sure it's just a matter of time before they get the GT2 RS at VIR. Depending on how much time they spend on each configuration, it could set a pretty good time. What would interest me the most is their full course time, that is the configuration we ran 99.5% of the time. The 1:51 is a solid time for the ZR1.

I only had about 5 or 6 laps on the west grand course, set the time and we went back to the full course because we were running a validation test. My objective was to match the Z06 time on the 1 mile patriot course which I missed by .5 seconds. A few more laps and I believe we could have achieved it. We did it everywhere else on the track. One final comment on the Grand Course lap is; I should have taken a 2nd warm up lap as the ambient was fairly cool. I struggled keeping the back of the car under me from turns 1 through 6, after that it was perfect. Nonetheless it is what it is.

Robert R1

If a GT2 RS is on the "R" tires, it'll be hard for any current car outside of the Senna to beat it at this stage.

And the Senna will only be taken down by the next set of hypercars: AMG One, Aston Valkyrie.

Still want to see a sub 25 at Laguna from the Senna.

RapidC84B

VIR Grand is worthless... everyone races on Full. The ZR1's 1:51.xx is astoundingly fast.

UnhandledException

Why doesnt somebody do a lap with these Michelin cup2 R tires to see apples to apples how ZR1 compares to GT2RS and GT3RS?

There has now been a number of different tracks where even the GT3RS with 200 less hp and more than 50% less torque beat ZR1s records. If its all due to the tires alone then that would settle the debate.

I’ll tell you my real world experience. I “played with” a 991.2 GT3 recently and they are extremely fast and agile. It was surprising how he was catapulting and changing direction at the same time. A car is more than just numbers I guess.

Poor-sha

Because they don't have sizes for the ZR1. If they did, I'd buy a set for my GS.R to test as I need a "street tire" if I'm going to run Grid Life track modified class and right now the Khumo is the tire to beat but also don't fit.

Jim's 1:51 on VIR Full is insanely fast. My best lap in that car was 4 seconds slower and I was on Pirelli DH scrubs. Just incredible. I imagine the cooler weather and auto trans helped though as he was significantly faster at the end of the back straight even with relatively similar launches out of Oak Tree but damn is Jim a great driver.

range96

Those tires are not available in the ZR1 sizes. I'm sure if you made a financial contribution to the cause (think big numbers), you could talk Jim Mero into trying to get better times at the Ring (with slicks or Hoosiers on the ZR1).

range96

Haha, I keep posting and seeing you beating me by a few seconds. Same as it would be on the track.

Robert R1

Here is the time difference between a Porsche Cup 2 and Cup "R" If I recall, the Corvette Cup tire is more aggressive than a Porsche Cup tire but still not close the "R" version.

UnhandledException

Thanks so its about 2 seconds. So ZR1 is head to head with gt2rs.

Telepierre

I am still bit puzzled by the CUP 2 Rs used in conjunction with the terms road legal track tire and production car.
My understanding from Jim and the Corvette track record videos is that the track cars are configured the same as production cars you and I can buy at the dealership. It is my understanding the production ZR1 is standard equipped with "regular" CUP 2 and I suppose the production "claim" stems from passing FMVSS with those exact tires. One tire one FMVSS?

For the GT cars, it is my understanding, "regular" CUP 2 are THE production tires (for FMVSS as well I suppose) and the CUP 2 Rs (yet to be determined if they are really for sale tire rack notwithstanding) installed and tuned for the track.

Can a manufacturer submit multiple tires for FMVSS?
OR
Couldn't Jim or his heir apparent {(:-)} install track tires, tune then accordingly and post a record as "production car on road legal track tires? I have a hunch that would not fly?...

P.S. The Ferrari 488 Pista (mentioned above) was equipped with CUP 2 K2s and not Rs

Ninetres

Jim several times you discussed the importance of the optimum temperature window for the cup 2s being so critical for maximum grip. Please walk us through what you'd do during an out/warmup-lap (or 2???) on your average 2-3 mile road course. What are you doing behind the wheel? What percent effort are you pushing the car? Focusing on getting heat in brakes too? Etc....

Any data as far a needle temps across the tread surface we should be shooting for if we dive into the hot pits?

New ZR1 owner. Thanks!!!

Jim Mero

Hi,

Congrats on the new ZR1.

It all depends on the ambient which translates to track temperature. The Cup 2 tires are awesome but they take a bit more time to come in when completely cold than the Cup 1 tires,

Typically on a 2 or 3 mile road course I get aggressive as I can pit out. I have PTM and stability off so I can spin the rear tires. I choose a turn, typically a slow one where I need full grip with a hot lap throttle apply. If the grip is not there, I'll take a 2nd lap. If the grip is there, I will put the car in race mode 5 (ZR1) and go hot. The slow turn is a go/no go for me. There have been circumstances when I have gone hot with questionable grip in that particular turn. But, having that question mark in the back of my mind forces me to be somewhat tentative until I am sure of full grip.

Relative to the brakes, the only issue is the burnish. There have been a lot of times when we had pre-burnished linings. The brake group at the Proving grounds would burnish them for us. If the linings are burnished, there's nothing to do to prepare them on a warm up lap. If I have to burnish, its a bummer because it takes 4 laps for the burnish and the cooling. Whenever we are doing sessions you always look forward to those first 2 laps with peak grip, 4 laps of burnishing takes just a few percent of grip out but enough that the lap time will be just a bit off compared to just a warm up lap.

Typically the only time we stick the tires are in the development process tuning the tire. It's important to see the temperatures of different compounds. When we are then running on production tires we typically don't stick them because temperatures across the tire is an indication of camber setting. As you probably know we are limited there.

Hope that helps,

Jim

RapidC84B

Jim - When you run the cars for lap time what alignment settings are you on? OEM, OEM track recommendation, or something more aggressive? I.e the Z51 at the ring on MPSS tires, what alignment do you run for that?

Jim Mero

OEM track recommendations every time. I can't remember if we recommend x weights in the owners manual. We do set the cross weights to 50% with my rear end in the car. The car from bowling green comes out very close to 50%, but after we align it to track specifications we always re-check. typically they're within 1 percent before we adjust.

Ninetres

Thanks for the insight! Good advice. I gotcha about alignment....but even after our temps are stable across the tread, we still grab readings to build data for noticing any trends if the tires seem to perform better around a certain temp over a single lap (I race time attack). But we have very little data opposed to a program like you were/are a part of. I guess eventually the data would become redundant (same tires/track/alignment/weather that we have lots of data for etc).

Robert R1

Finally! Thank you for this. The amount of time I've heard to "take a few laps and ease into it." I've always nailed it coming out of the pits and in anything but sub 50 weather, they were fine by end of lap 1. On a warm day, they'd be fine well before then. Same with brakes (outside of annoying burnishing). This is cup 1 and 2 on a c6z/07.

For on track burnishing, I'd just do 2 gradual build up brake pressure laps, 3rd lap would be hard braking to a soft pedal and then 4th lap was a no brakes cool down lap. Then park it and let it cool down fully and go back out drive normally. Is there a better procedure for doing it on track?

usrodeo4

Interesting...I owned a 750+BHP 997 TT and I ran the Cup 2 R tires...what I noticed over the Cup 2's was how linear the traction loss moment was and how easy it was to "feel" and adjust to it. If I could ask a question, have you ever tested the Good Year F1 RS tire and if so how do they compare to the Cup 2 R tires?

meadowz06

Jim is a class act. And a huge asset to the Corvette community. I am really glad Jim did not get injured in any of his Corvette testings. It takes huge ***** to drive like Jim. And I think we will soon find out, that the ZR1 was on par with some high dollar cars at the Ring. Like he said, a lot of skill, and some luck.

The Blue Beast

What do you mean by "shock temperatures into the tires ' ????