2009 Chevrolet Corvette ZR1 testing on the Nordschleife (pictures included)

[culver]

I'm curious how much faster the Corvettes (or other cars) would be with R-compound tires. I could see a standard Corvette Z51 with R-compound tires pulling similar lap times around a track as a factory floor Z06. Of course that's a bit of a problem when comparing ring times. I might consider say a Miata stock even if you put new tires on it. However, when we start playing the ring time game are we really talking "factory floor"? How much of the various lap time differences are due to tires vs other factors? This is why I have heard people say the car magazines should compare cars with the same tires. I also suspect really grippy near R-compound tires is PART of how the 911-GTx's have turned such fast lap times. I suspect if the previous Z06 times was on run flats the car probably left some speed on the table.

Lots and lots of variables. Either way, I guarantee my magazine is faster than yours!

[2ndclasscitizen]

You can speculate as much as you like about the tyres, but if Porsche/Ferrari etc choose to put good tyres on their cars and Chevy don't, that's Chevy's problem.

[LeonOfTheDead]

these two cars are very fast,no doubt, but i'm not so sure about how much the times can improve. i simply consider this fact: pagani zonda f, club sport edition, professional recing driver: 7:28
you all know its performance and technical stuff. carbon fiber chassis and 650 hp, among others...and 500 kg less than the gt-r IIRC

[billygoat081992]

sick! its going to come in red!! awesome!!!!

[culver]

You can speculate as much as you like about the tyres, but if Porsche/Ferrari etc choose to put good tyres on their cars and Chevy don't, that's Chevy's problem.

First, it was not meant to be a hostile or condescending post. I assume yours was also not meant to be.

Second, it's not "crappy" tires, it's simply different tire choice. Tires are very easy to change so to some degree it's like going to Brooks Brothers and saying a suit looks bad simply because it's shown with a bad tie. The tie may make or break the look but it's also easy to change. Also, GM may have good reason to choose the tires they do. The stickier tires may have simply unacceptable performance in cold or rain. GM may have decided no car should be sold without some proper provisioning for a flat. Run flats would count, no spare and regular tires would not. Perhaps the various companies decided that one tire or another made the car feel better or made it more progressive and easier to drive even if it did add a few seconds to a long lap.

I recall a number of reviews for the '99 Miata that actually said the car was more fun with the less grippy base tires vs the faster Sport Package tires.

Also note that Porsche decided to put "crappy" tires on most of their cars. None of them, that I'm aware of, have gone 100% and used Hoosier DOT-R race tires. All would be faster with those.

I'm simply speculating about how much of these 5-10-15 second differences might have been due to choice of tires for what ever reason (perhaps even very good reasons). It would be interesting to have some idea how much different various times would be with different tires.

BTW, I believe Car and Driver talked about this very topic a while back. They were discussing the pros and cons of equalizing the tires by testing all the cars with the same tires.

[Matra et Alpine]

Also note that Porsche decided to put "crappy" tires on most of their cars. None of them, that I'm aware of, have gone 100% and used Hoosier DOT-R race tires. All would be faster with those.

hmmm, try some Michelin SPort or Yokohama 008Rs or Pirelli P9000.
Assuming "Hoosier" is better than the tyres already available to the top manufacturers is a little us-centric

It would be interesting to have some idea how much different various times would be with different tires.

I can add or take away a second per lap just by changing the tyre PRESSURE, never mind construction, compound and tread

BTW, I believe Car and Driver talked about this very topic a while back. They were discussing the pros and cons of equalizing the tires by testing all the cars with the same tires.

Confirming how dumb C&D journalists can be sometimes.

Ross Brawn, Ferrari F1 Technical Director[/I]]"To me it's one-third car, one-third tyres, one-third driver. All those have to be at the highest level or else you won't succeed."

Beyond cheap econoboxes, "performance" cars are designed with a certain compliance in the tyre wall and suspension geometry to match tyre distortion to get the right under/oversteer characteristics.
Michelin remanufactured the tyres for the Matra because the newer lower profile rubber made the car impossible to corner at speed as it was DESIGNED to use the compliance in the tyre wall as part of the suspension.

[culver]

Not claiming Hoosiers are better, just using them as an example tire. I'm sure other manufactures also make good R-compound tires. Please don't assume that just because I say "tire" vs "tyre" the intent is US centric. I also happen to be a native Hoosier.
As someone who has spent years around race cars I do understand all the tire pressure comments.
Actually I think C&D made very good points. They were basically saying why they wouldn't do that. Please don't be so quick to condem as I suspect you would agree with their logic. IIRC it was something to the effect of:
1. The manufacture knows the product best.
2. One particular tire may be better suited for car A than B (your next point)
3. The as it would be difficult to pick the "fair" tire for all cars it's better to simply let the manufacture choose and go from there.

The whole point of my post was that a manufacture might not choose the tire that would deliver the absolute maximum lap time thus car A might turn a slower lap time than car B simply due to tire choice yet the reasons for picking the tires could actually be good ones. I strongly suspect you actually agree with what I'm saying.

Not being a fan boi here.

[Juggs]

I have heard reports of it (the ZR1) running unnofficial lap times in the 7:40 range with engineers behind the wheel on a cold wet track

[clutch-monkey]

seems respectable enough

[Matra et Alpine]

Not claiming Hoosiers are better, just using them as an example tire. I'm sure other manufactures also make good R-compound tires. Please don't assume that just because I say "tire" vs "tyre" the intent is US centric.

hah, my bad, exactly the "trap" i had fallen in to

Actually I think C&D made very good points. They were basically saying why they wouldn't do that. Please don't be so quick to condem as I suspect you would agree with their logic.

No, because the logic is flawed 100%.
Why stop at the tyres ? What about the shocks and springs and wheels and then how about gearbox, engine, suspension geometry, suspension components, chassis mounting points .... etc etc etc.

Manufacturers chose a tyre the same as the chose every other component and so they must stand and be measured by that choice.

One tyre will always suit one vehicle more than another and that says nothing about the tyre OR the car other than their match. Assymentric tread versus standard, wall strength, phicycial versus compund grip, compound flexibility. and many other things. NOne of which are ever right or wrong unless matched to the wrong car.

The whole point of my post was that a manufacture might not choose the tire that would deliver the absolute maximum lap time thus car A might turn a slower lap time than car B simply due to tire choice yet the reasons for picking the tires could actually be good ones. I strongly suspect you actually agree with what I'm saying.

With THAT part I agree.
So someone choses the compromise of run-flat tyres rather than having a spare or heaven forbid having a customer actually have to wait for a recovery vehicle to get a new one.
Some chose long life, some chose grip.
THe RX-8 is a perfect example. The bridgestone 040s are OK in dry but poor in wet when trying to get some performance. THe 050s are MUCH better in the wet and marginally better in the dry. But evidence has then 050s wearing quicker ( 6000 miles versus 10000 miles - both driven "hard" )
Also, profit. With 4 (or 5) tyres with every car sold then a $10 difference adds up to a LOT of money on a compnaies bottom line.
So when you look at a "normal" Porsche, BMW, M-B etc you see a farily normal tyre used in a number of vehicles. BUT go to the performance cars and you find tyres used on a very limited number of vehicles. Ones where they know the owner will accept the compromise in proce or life for grip.

Not being a fan boi here.

yeah, my bad

[culver]

When C&D was talking the tires they were responding to a reader who asked why they didn't equalize the tires. I think this was just after the previous gen Civic Si did badly in a comparison in large part because it came with all season tires vs the 3 season tires the Ford came with. Basically, they didn't do it for all the same reasons you were giving. They also said it would be expensive

:toast:

[CircuitHero]

i'll still be waiting for someone other than nissan to do either time with a GTR they bought off the showroom floor.

You might be waiting a while, the V-spec isnt due out until 2009/10. There is also a rumoured 'Evo' spec still to come.

Manufacturers chose a tyre the same as the chose every other component and so they must stand and be measured by that choice.

+1

Its not as if they just pluck a tyre choice out of a hat. Ridiculous amounts of R&D goes into tyre choices. Its all very well saying ''x tyres would work better'', you could then find that in that particular size, the sidewalls are too soft, or by the same token too hard. Certain tyres work excellently on certain cars, and in certain sizes. What works favourably on one car could work terribly on another. Lets not forget, although the GTR and Z06 are both cars, theyre worlds apart in the way they deliver their performance.