BWAHAHAHAH

Tire roll and sidewall buckling are two different things. You'd know that if you actually drove. Your camber setting can be fine and suspension stiff and you still bend the sidewall under cornering, in fact that makes it more likely because added camber increases grip (to a point) and if the suspension is stiff, the only thing left to give is the tire. And by the same token you have have perfectly stiff sidewalls and still roll the tire due to inefficient camber settings or too soft of settings with the damper.

Let's call it excess sidewall flex so your inexperienced mind can comprehend it. It IS NOT the same as rolling the tire because your dampers are too soft or you don't have enough camber.

Your logic is awefully poor, lighter wheels has hardly any effect on the force exerted on the tires during cornering. And for the last time I have not said anything about non-runflat tires being poor. So stop with your drastic over statements.

Your comprehension is also poor, because I never said the tire would fail quickly. But have you asked yourself why a manufacturer trying to make a performance vehicle would put a tire on the car that can't support the car during max cornering???????

I also sated clearly that the same squirmy feeling that your favorite magazine suggests are more than likely the sidewalls bending under cornering.

And what do we have here, more magazine references........... You sound an aweful lot like......

HAHAHAHAH I know who you are! YOU STILL HAVE NO CLUE!

 

I didn't say anything about lighter wheels having an effect on the force exerted on the tires during cornering, so there is no poor logic there. Horrible assumption, heavy.

You said "buckling":
"The GT-R will buckle sidewalls on soft sidewalled tires creating a slippery loss of grip effect."

They never mentioned a slippery loss of grip. How do you know the squirminess migh not be the effect of a less aggressive tread design? Ie, smaller treadblocks. The P Zero (non Corsa) is a less aggressive track tire than the Dunlops or Bridgestones.


But have you asked yourself why a manufacturer trying to make a performance vehicle would put a tire on the car that can't support the car during max cornering???????
Well, obviously hey wouldn't do that. But notice that the heavier M5 and similarly heavy M6 do just fine on non-runflats, even the M6 with R-compounds (which you can order that way from the dealer). Point being, you can support a 3900-lb car during max cornering without using runflats.

 

You tried to compare the runflats to all R-compound tires in a big group. There are no other tires that are going 2-3 seconds faster than the Bridgestones and nothing reported to have beaten the Dunlops at all. Are you even reading what you're typing?

A tire does not have to be a runflat to have a stiff sidewall einstein!!!!!!! However most street tires are developed with comfort in mind and therefore limit the stiffness of the sidewalls. When you bring R-comps into the picture it's a different story.

My goodness man!

Buckling and bending are the same thing. I consider buckling bending outside of the normal range of motion because the car has exceeded the resistance limits of the sidewall. I've explained it just fine, you just don't understand anything.

I've driven on Pzero's


In a 3800 lb car at very fast speeds.


And the tread is just fine! Tread squirm is not all about the aggresivness of the tread blocks. Bigger blocks do not alleviate trade squirm.


Experience, experience, experience.

Have you driven an M5 or M6 on track?

Let me guess.

NOPE.

Well I have and they are both oversteer happy machines as M's have been since their inception. They also have much softer suspension rates than the GT-R, less chassis bracing, and RWD.

Go back and read your lesson on what I taught you about what effect a softer suspension has on the sidewall of the tires.

 

Randy Pobst was testing Toyo's development R888's on the GT-R at Buttonwillow. He was going just as fast as on the Dunlops, which proved to be as fast as the Bridgestones. These were only prototype tires, so they had not yet struck the right balance. Another GT-R owner has reported 2.5 second improvement over RE070's with RE55's. If the the stock R-compound runflats are so great, then why do all the serious roadracers and autocrossers change their tires, or go looking for 20" aftermarket R-compounds which are virtually non-existent?


Where did I say it does?
I doubt the P Zeros have as stiff a sidewall as the OEM runflats. The point is that they did not hamper the GT-R during testing, and if they showed any tendency to roll under hard cornering, I seriously doubt Nissan would allow their participants to continue with them, and I also doubt Nissan would let Evo test a car with tires like that.

Wait, who said it was ALL about the tread blocks? Go back and read my post carefully, heavy. I offered a possibility as to what might have contributed to the tread squirm, and you're jumping on this as me saying something I clearly have not. Are you saying there's zero difference in tread squirm between an all-season type tread pattern and a genuine semi-slick when both are of similar compounds?

Oh, wow. You've driven an M5/M6 and found it to be oversteery. Nothing in that experience of yours indicates that the M5 can't be supported on non-runflats. Most of the time, the GT-R is also RWD. Clearly the M6 can be supported on R-compound semi-slicks, as was proven by the supertest, as well as by the fact that it can be ordered from the factory with those tires.


Let's get back to the issue of the Nurburgring, heavy. What is your technical explanation as to why HvS could not get within 16 seconds of Porsche's time in the Turbo? Don't give me any crap about other Porsches. We already know HvS is experienced in Porsches and that Porsche reports their times conservatively, more often than not running with traffic. I'm asking you specifically about the Turbo, an AWD car on semi-slicks which you say is ridiculously easy to drive to its limits.

 

NO

It goes more like this:

Randy was easily doing 1:57 min laps consistently on the Dunlop runflat SP Sport 600 cct tires which are standard on the GTR as well as the Bridgestone runflat RE070. All tires were set at 26 psi during the entire test day. He also ran about the same 1:57 time on the R888's that Toyo was testing. I asked Randy not to push the car to the edge and asked him to keep the transmission temp under 250 degrees F and he easily accomplished this while keeping the low temp on the transmission and not trying to set a record pace.

and then:

Randy actually said that my stock car handled much better with superb balance on the Dunlop runflat tires than the R888's that he was testing for Toyo.

You are , I didn't want to look up the info so you found it for me, this is the same day pro driver with Dunlops outperforming the R888's. And this is only one test, the other is from Australia, but I'm too lazy to look it up.

You = Fail.

I don't even know why I'm bothering with you, you skip over all the posts about experience, because you haven't even driven a go-kart. Your posts make no sense, all conjecture and magazine articles. You completely leave out the part about the suspension stiffness. The GT-R has something like 900# springs on it, with aggressive damping, M5's ride is WAY softer! You also forget the M5 can't sustain the cornering g's that the GT-R can, and that their tire compound is not as aggressive as either of the GT-R's tires.

Most street tires sidewalls cannot support the GT-R's tire stickiness and weight. If you make the tires less sticky, then it will slide, alleviating some of the buckling.


Let's go back to the Nurburgring?



How about you go to any track and ACTUALLY DRIVE A CAR ON IT!!!!!


Done with you.

 

On the contrary. Everything you posted there supports my statement: Both the prototype R888's and the Dunlops were lapping in the same time (1:57). I also said that since these were only development tires, they had not yet struck the right balance. I never said the prototype tires were as balanced as the Dunlops. Look at what I said many posts ago:
"Some GT-R owners say the car has more grip on the R888's, others say the balance isn't as good (but not slower)."
You have a hard time reading. But I figured just as much from your C&D Lightning Lap BS.

The Aussie test you were talking about was comparing lap times from the year earlier. They weren't same-day tests.

Also note the rest of that guy's post:
"Randy also mentioned that my car was so much better and more powerful than the Red GTR test car they used in the other test. Basically the Red car was a dog.
My point is...a completely stock GTR driven by a pro driver is an amazing tool that can easily break track records."

There goes the theory that Nissan are sending tuned-up ringers for press testing (but we already knew that from the TopGear test on the autobahn with the Turbo). This customer car was better and more powerful than the Nissan-supplied press car in the Motor Trend comparo, which already beat the Turbo even when driven by an experienced Porsche racecar driver.

Show me proof, not rumor or innuendo, that the GT-R's tires are stickier than the P Zero Corsas on the M6. The fact that you even mention the M5's spring rates shows you can't predict that a non-runflat tire will roll/buckle based solely on the weight. There are other factors.

So basically you're a hypocrite and won't call out Porsche for cheating when the time difference is 16 seconds in a type of car with which HvS is already very familiar. And Porsche even times their cars conservatively.

Ok, bye.

 

Guibo, it would be worth my time to fuss with you if you actually had some driving experience, but all you have is what you read and with the variety of verbage and opinions on the net you couldn't possibly think you can derive any real baseline for what you're talking about from purely reading.

You can continue you dribble, but until you actually drive a car on a track, your opinion is utterly worthless. I get PM's constantly asking advice on suspension, tire setups, brakes etc etc etc. and that's because I have experience and know what I'm talking about. Who would want your opinion considering you've never even driven on a track? And who would bother even paying attention to what you say if all they have to do is read all the magazines and surf the net to equal your knowledge level?

Seriously, at least try and experience something before you act like you know what you're talking about. When it comes to Nurburgring, ok, neither of us were there so that's conjecture from both sides, but your opinion is still marred by the fact that you don't know the slightest thing about driving on a track. Give it up.

 

What does that have to do with your erroneous claim about BMW's sharpest driving machines (M cars) "giving up" runflats? Wouldn't they need to have them in the first place in order to "give them up"? Hint: An M car isn't a base 3 or 5 series with better parts slapped on. The engine, suspension, and driveline are typically ground-up designs.

Thanks for that update. I don't beleive the M6's suspension and drivetrain are close enough to the GT-R's for your example to have any real relevance. I also believe hc's point was that the GT-R's handling is pretty well optimized for the OEM runflat tires and that those runflats provide enormous grip. Arbitrarily swapping in R-compounds is not surefire recipe for improved performance. It's also kinda odd Nissan would deliberately "handicap" a track assassin like the V-Spec GT-R with those godawful runflats.

Thanks for the correction. I would have never in a thousand years caught that. When it comes to pedantic fact checking, you're #1!

 

New reports are in, the ZR1 has just ran Hockenheim. A longer track should see the ZR1 stretch its advantage through higher hp. The GT2 was also way faster than the GTR. Like ive said before the GT3 and GTR are closer in performance, the GTR is actually a low 7:40's and high 7:30's car, not a 7:20's car.

1. Donkervoort D8 RS06 1:04.8
2. Maserati MC 12 corsa 1:07.6
3. Porsche Carrera GT 1:08.6
4. Radical SR3 1:09.1
5. Mosler MT 900 GTR 1:09.2
x. Corvette ZR1 1:09.7
6. Porsche 997 GT2 1:09.7
7. Koenigsegg CCR 1:09.8
8. RUF RT12 1:10.2
9. Ferrari 430 Scuderia 1:10.3
10. Porsche997GT3(facelift)1:10.4
11. Nissan GT-R 1:10.7

 

Aside from Nurburgring, you haven't even driven a GT-R on track yourself, so your experience in other cars is not as relevant as you seem to think. I'll take the words of Pobst, Dale Lomas, and Jethro Bovingdon over yours anyday. They have given their assessment of how the GT-R drives after having driven it. Must I have driven a Veyron to conclude that it's f'ing fast? Must I have driven a Murcielago to conclude that Chris Harris was faster in that car than HvS?
We were not both there, so how can you come to the conclusion that Nissan cheated while Porsche did not? You yourself said an AWD car on R-compounds is an easy thing to drive, there's nothing mysterious to it, yet when such comments are directed at the 997 Turbo, you apply a double standard and believe wholeheartedly that Porsche could not possibly have cheated, even when the margin between HvS and Porsche is greater than between HvS and Suzuki. At what point are you going to critically say to yourself "hey, something's not right about Porsche's claim for the Turbo and what HvS got"?

 

My point is that BMW's sharpest driving machines that are at least comparable to the GT-R in weight give up runflats and are better for it. The 5-Series, 3-Series, and 6-Series all have runflats in the first place, so they do "give them up."
Pedantic? Maybe I should have said "every single M-car based on a car that had runflats up until the X5/6" has ditched the runflats. Would that make you happy? I'm sure you're probably thinking of some obscure example to pick holes in what is otherwise an accurate statement in the big picture.

It's not really odd. I don't know the specifics of the contractual agreement between Nissan and Dunlop and, I'm guessing, neither do you. And where are they going to put a 20" spare anyway? The GT-R has a decent trunk, but it's not that big.
RE: optimization
The Z06 has been optimized for its OEM runflats, yet how many Z06 racers keep them for serious track work? Not many. The old C5 Corvette with Z51 also had tires optimized for it, yet when C&D switched to the non-runflats of the C5 Z06, it knocked 2-3 seconds off of a 60-second lap.
I'm sure the GT-R has been tuned to perform well with its runflats, but that doesn't mean other tires won't perform better. OEM components are usually built to a cost (and/or contractual obligation) anyway. It doesn't mean a particular component will give the fastest lap time.
In any event, the Turbo on its optional MPSC's would still have been slower than the GT-R, and still slower even if the GT-R had been on the slower Bridgestones.

 

That is a great result for the ZR1.

Interestingly, the GT-R is:
- 3.1% slower than the CGT on Hockenheim, yet only 1.3% slower on NRing.
- 1.4% slower than the GT2 on Hockenheim, 1.1% slower on Nring.
- 0.4s slower than the Scuderia on Hockenheim, 1s faster on NRing.
- 0.3s slower than the GT3 on Hockenheim, 2s faster on NRing.

The GT-R is a 7:20's car, with Suzuki driving.

BTW, Sascha Bert has the following comments on the ZR1 (roughly translated):
"The ZR1 [scheibt] like hell, has steam in all situations owing to the compressor. The steering element is super direct, traction and grip are extremely high. The vote from the dampers and differential is perfectly managed, which also applies for the tires. I have never driven a road tire with so much adhesion. However, I like the brakes best. There is no fading, and the ABS is perfectly tuned for the racetrack."

 

So why is the GTR vastly inferior to the ZR1 and GT2 around that track? It certainly doesnt have enough power to stretch its legs on a very long and high speed track like the Nurburgring. GTR is at best a 7:38 car and most likelt a high 7:40/7:50 car.

 

a) I appreciate the more civil tone - it makes your posts more readable.

b) A better example of a car the GT-R's weight that "gave up" runflats would be the CTS-V. The wheel & driveline components of the standard 3 and 5 series cars never come into play as far as the M cars are concerned.

c) The Z06's runflats don't provide the grip the the GT-R's Dunlops do (Per SA SuperTest), and the Z06 weighs significantly less. IOW, not all runflats are equal. Just because the Z06 enjoys an improvement with a tire swap does not mean the GT-R will.

d) Nissan has contracts with two separate tire makers for the GT-R and specified runflats for both. In fact, both tires were specifically designed for the GT-R, if memory serves. Take a look at this article. It seems to indicates runflats were chosen for their ability to maintain a "large grip tire area" under heavy loads:

http://features.gtrforums.com/article.php?id=8

This also seems to confirm some of the things heavyChevy was saying.

 

We've been over this before. Its weight seems to affect it more on a tight track. Didn't you notice the Focus RS outcornering it in the tightest turn on the Contidrom, yet on the fastest turn, the GT-R was 12.5 km/h faster than the GT3?
It was slower than many other cars on the autocross track in R&T's comparo, yet 2nd fastest on the speedway (only behind the GT2, and ahead of the LP560).
Look at the Motor Trend test: the GT-R was dead last among 4 cars on the tight 1-minute track, slower than even the 599. Yet on the 'Ring, it is 9 seconds faster than the 599.
Also, the Hockenheim track is smooth. The NRing is much bumpier, and the GT-R handles bumps better than most. Additionally, the more gearshifts there are, the less time it loses against other cars.

Your comment about the GT-R not being able to stretch its legs on the fast NRing is unfounded, and has been contradicted by those who have driven the car.