TYRES

[Zaphod]

From MotoGP news.

Track temperatures hit the 40°C mark for the race, which was more than 20°C warmer than last year’s Dutch TT. Tyre selection for the race was fairly similar to that for qualifying, with all riders selecting the harder front slick option for its greater cornering stability, while rear tyre choice was more varied with thirteen of the twenty riders selecting the softer rear slick.

Hiroshi Yamada - Manager, Bridgestone Motorsport Department

"Today’s race was held under sunny skies and the fans that came to the circuit witnessed a fantastic race with many interesting battles throughout the field."Which race was he watching ? "Congratulations to Casey and Repsol Honda for a great win in what must have been a tough race. It was unfortunate that Jorge had some bad luck and couldn’t challenge for the win and I am sorry that some riders experienced tyre problems during the race. We are now investigating the issue and will report back to teams with our findings at the next race."


Shinichi Yamashita – General Manager, Bridgestone Motorsport Tyre Development Department

"Today’s Dutch TT saw warm track temperatures and the race was run at a good pace with all riders selecting the harder front slick, while all but seven riders selected the softer slick option for the rear. Unfortunately a few riders experienced a problem with their rear tyre today and we sincerely apologise to those riders affected. We have commenced a full investigation into the matter and I will personally take the affected tyres back to Bridgestone’s Technical Centre in Japan where they will undergo detailed analysis to determine the cause of this issue."


My question is......

40 degree track temps. Who's doing the R&D ? Surely we can expect to see higher track temps, for starters, at Laguna or any of the Spanish rounds ?

quote....
Track temperatures hit the 40°C mark for the race, which was more than 20°C warmer than last year’s Dutch TT.


Do they really construct and fly in circuit specific tyres for each round ? ..that is how I am interpreting this statement regarding the failures....



I'm still in the poor Quality Control camp until someone can give lazy ol' me a breakdown of who was on what tyre, and how many on the same compound, as say Rossi, finished with no tyre dramas. The argument could be put forward that it's down to the crappy ol' Duc.....except that it happened to Yamaha's as well.

In regards to the Honda's and their covered rubber in Parc, any shots of those going around ?

Was it their existing tyre wear problem, or similar to these catastrophic (near enough to !) degredations experienced by others ?

[Gar]

Track temps will probably not be too high at Laguna. It's generally pretty cool there, although everyone still remembers the freakishly hot one.

[redmike34]

I just moved to Monterey. I don't know what temps will be like in 27 days, but right now there are people wearing windbreakers around here... I never saw the sun today and it was only about 62F for a high temp.

[Zaphod]

OK, ok !! I just guessed with Laguna....it's California, and I presumed it was warm-ish all year 'round.

[Nucci]

At circuits where hotter temperatures are expected or where tyres generate more heat, harder compounds are provided. And yes, specific tyres are made for each race but they are shipped, not flown in for each race.

[Nachlauf]

Of course they send specific tires for each event. They developed several compounds only because there are different conditions depending on where you race. Last year I had the impression they generally brought versions for higher temps which caught them out more than once. Maybe they are bringing compounds for lower temperatures this year and are caught out again?

Anyways, it is unacceptable, that tires disintegrate without the riders doing anything out of order. This must not happen!

[sir_nj]

OK, ok !! I just guessed with Laguna....it's California, and I presumed it was warm-ish all year 'round.

your thinking inland SoCal there Zaphod, even San Diego can get cold(ish) as its right next to the Pacific.

The hardness of the compounds and degree of assymetry is specific to each track. However, even if they get the predicted track temperature out by 20degC they shouldn't get anywhere near that degree of chunking/delaminating. Instead they normally get faster tyre wear than expected so it's like ice skating for the last third or so of the race.

The delamination seen on Rossi's rear and presumably a similiar thing on Spies' rear is not "wear" but a failure of the tyre and I would think it is mostly due to QC as you suggested. Oscar suggested on another thread that some of the QC variation can be attributed to storage but for my money I would be going back to the factory and pull apart all the tyres they still have in that batch and look at the boundary layer between the main carcass and the top rubber. To lose such a big chunk suggests it was never glued in the first place.

Delamination is nothing new but to see it on more than one bike and presumably from the same batch of tyres suggests it was not a fluke.

Do you remember Mick having a massive chunk of rubber fly off his rear and he sat the bike up causing Schwantz to go straight. The idiot that was D. Eslake (spelling?) started saying how unprofessional it was etc unitl Sheene pointed out when watching the slo mo that when you have such a big chunk fly off your tyre you have no choice but to sit the bike up.

[yzr750]

Maybe it's just 260hp bikes allied to the extra torque and weight this year that means the tyres just can't cope? The extra weight will have a bearing on tyre longevity, Rossi and Spies are two of the heaviest riders, and they seemed to suffer more than anyone else. I remember when the TZ750's first came out, the current tyre technology at the time couldn't cope with all that power and weight, and it needed a lot of work by the tyre companies to get the tyres to stop destroying themselves. It could be that the bikes are a fair way ahead of the tyres, and bridgestone are playing catchup.

[sir_nj]

Maybe it's just 260hp bikes allied to the extra torque and weight this year that means the tyres just can't cope? The extra weight will have a bearing on tyre longevity, Rossi and Spies are two of the heaviest riders, and they seemed to suffer more than anyone else. I remember when the TZ750's first came out, the current tyre technology at the time couldn't cope with all that power and weight, and it needed a lot of work by the tyre companies to get the tyres to stop destroying themselves. It could be that the bikes are a fair way ahead of the tyres, and bridgestone are playing catchup.

not certain the extra 10kg out of the total ~200kg is the reason that Spies and Rossi had delamination. Throttle control is likely to be a big part but would have to suggest that despite the 260hp the biggest demand on tyres for motorcycles was the Datona 200 when they raced superbikes. Those tyres blew apart not chunked. Can't remember the last time a MotoGP tyre exploded, waaaaaaaaaaaaaaaaay waaaaaaaaaaaaaaaay back, nope, still can't remember a motoGP tyre letting go like the Daytona tyres.

[Zaphod]

Throttle control is likely to be a big part

Too random for my liking. Rossi and Pedrobot are known to be smooth operators on the throttle. Don't know about Spies, looks a bit more gung-ho on the fruit-juice.

It wasn't down to one manufacturer, one style of riding, one ETC set-up or one type of engine power delivery.

...Has to be QC. I agree, storage doesn't do it for me.

Tyre manufacturing/production issue.

Of course, their will be a totaly inane explanation proffed by Budgetstone that defies anyones ideas of how it could have come about.


PS, last catastrophic tyre failure I can think of was B.Sheene at Daytona.

[Cam D]

+1
QC for me as well. Neither Rossi or Spies or Barbera have a history of destroying tyres up till this meeting. Makes me wonder about Casey's "dodgy" tyre for the week before. Never got a good look at it to see if there was any damage.

[Gar]

PS, last catastrophic tyre failure I can think of was B.Sheene at Daytona.

Remember Nakano at Mugello?

[Zaphod]

No I didn't !.....thanks for the heads up.

Have been trying to find footage of it, but it doesn't seem to exist.........wonder why ?

Over to you Bridgestone......

[Gar]

Have been trying to find footage of it, but it doesn't seem to exist.........wonder why ?

:20 mark

http://www.youtube.com/watch?v=n2xA7bssWBg

Dunlop had several failures at Daytona a few of years ago in testing, and I think someone else had a catastrophic failure the same year as Nakano.

[Cam D]

Have been trying to find footage of it, but it doesn't seem to exist.........wonder why ?

:20 mark

http://www.youtube.com/watch?v=n2xA7bssWBg

Dunlop had several failures at Daytona a few of years ago in testing, and I think someone else had a catastrophic failure the same year as Nakano.

I remember reading that his parents never went to the racing, but they turned up for that meeting. Poor buggers must have had a heart attack watching their boy cartwheel down the road.

[sir_nj]

PS, last catastrophic tyre failure I can think of was B.Sheene at Daytona.

Remember Nakano at Mugello?

good call, had forgotten that completely

[Zaphod]

I did watch that earlier, but didn't pick it as a tyre failure.

.....I stopped watching when the words "New top speed crash world record" came up........

Shit like that is what turns the sport into a circus.

Anyway...back to topic.....

What happened there ? Flat, delamination or chunking ?

[Gar]

It blew up, to put it simply. He was over 180mph and accelerating flat-out at the time.

[Nachlauf]

I think it had something to do with the rim. Someone (Alex Hoffman?) said the tire didn't actually explode but lost contact to the rim. Of course it deflated instantly when that happened. How something like that can happen I have no idea.

[tz250w]

Dunlop had several failures at Daytona a few of years ago in testing, and I think someone else had a catastrophic failure the same year as Nakano.

Didn't Tamada have one go the same weekend at Mugelo? I seem to remember him pulling off the track and parking it with a destroyed tire. Could be a different year entirely though, I tend to mix them together these days.... lol

And Daytona... The banking is probably more to blame than anything else. With the G's induced, you couldn't run a "normal" tire at the "normal" pressures and expect normal results there. Bikes on the banking at Daytona almost look like they're upside down when you stand in the infield.

[raisinberry777]

You're right, Tamada's tyre failure was the same race.

[Gar]

Yeah, I remembered there was another but didn't remember who. Tamada's was less exciting but more impressive as he saved it!

[Squidpuppet]

Wow. So Bridgestone doesnt take responsibility for the tire failures. Set up and riding style are to blame.

Whatever.

[Oscar]

Wow. So Bridgestone doesnt take responsibility for the tire failures. Set up and riding style are to blame.

Whatever.

BS by name AND nature. I'd like to see them explain how it was, since Rossi is (IIRC) their 'tyre development advisor' or something similar, they have failed to make a tyre that copes with Rossi's style and set-up. You could get away with that sort of crap if the only guy affected was, say, Elias who was known and accepted to be extremely different, but when the tyre fails worst for your chief test pilot?

I doubt we'll get to hear about it, but I can't see other than a lot of very dark muttering from the paddock over this, and rightly so.

[Zaphod]

From the main page.

Not a slight on Krop from my side, as I guess he's only printing the official press realease/interview........but,



Bridgestone explains findings of post-Assen tyre analysis

Friday, 6 July 2012

Following problems occurring in the rear tyre of three riders during the Dutch TT at Assen last Saturday, Bridgestone immediately sent the affected tyres back to its Technical Centre in Kodaira, Japan, where they underwent intensive analysis to determine the cause of the irregularities.

Bridgestone’s Manager of Motorsport Tyre Development, Shinji Aoki, was closely involved in the analysis of the rear tyres and here he explains what the contributing factors were at Assen that caused the problems in the rear tyres, and what measures Bridgestone will take to prevent such occurrences in future.

Aoki-san, can you explain what were the causes of the problem that some riders experienced with their rear tyres at Assen?

“There were three riders who had problems with the right shoulder of their rear tyre at Assen during the race, namely chunking of a piece of the tyre’s tread due to excessive heating of the rear tyre. Fortunately, none of the riders that experienced this issue crashed and the inner pressure of their tyres remained normal.

“At Assen there were some factors that contributed to this potential increase in rear tyre temperature. Compared to last year, the ambient temperature was substantially higher, the capacity of the engines in MotoGP machines has increased from 800cc to 1000cc which brought with it an increase in torque and machine weight, while the layout of the circuit also changed which resulted in a marked improvement in lap times.

“All these factors, in addition to the high camber of the Assen circuit, contributed to an increase in the potential for higher rear tyre temperatures and when combined with certain bike setups and riding styles, resulted in excessive heat build-up that caused tread chunking of some rider’s rear tyres. Though we were aware that this year’s Dutch TT would run under different circumstances due to the aforementioned changes in MotoGP machinery and weather conditions, we could not anticipate that these changes when combined with certain other variables such as particular riding styles and machine setup would result in such irregular rear tyre behaviour.”

Were the affected rear tyres defective or have a manufacturing fault?

“We performed detailed analysis of the affected MotoGP rear tyres from Assen, as well as other rear tyres from the same batch as the affected tyres and compared our results with analysis of a control set of tyres from another production batch.

“All these tyres underwent extensive testing, including a simulation on a specialised test rig that uses a drum rotated at high speed to test the durability and operating behaviour of each tyre. This analysis definitively showed that there was no manufacturing fault with the tyres supplied at Assen.”

Sachsenring is very hard on the left shoulder of the rear tyres; could a similar problem occur this weekend?

“At Sachsenring it is usual for tyre temperatures to be higher than at other circuits, so for this event we traditionally have supplied special construction tyres that are specifically developed to handle extreme heat levels. So although relatively high tyre temperatures are expected this weekend during the German Grand Prix, the tyres supplied for this event are more than able to cope with this increase.”

And what about at the Italian Grand Prix at Mugello which is the next race after Sachsenring?

“Our analysis of the data acquired from Mugello shows that this circuit is not as severe on tyres as Assen, though as a precaution we will produce and deliver special construction rear slick tyres to next week’s Italian Grand Prix.”

How will Bridgestone prevent this kind of problem occurring at future races?

“Bridgestone will re-analyse its data from each circuit, including Assen, and use the lessons we have learned from last week’s Dutch TT to carefully consider the safety requirements and tyre severity ratings for each circuit and will then decide if any additional events on the calendar should also be supplied with special construction tyres.”

For 2012, Bridgestone changed the construction of its rear tyres to make them less rigid. Was this a contributing factor to the significant increase in rear tyre temperature some riders experienced at Assen?

“No, the difference in construction between last year’s tyres and the 2012 specification was not a contributing factor to the generation of extreme temperatures on the edge of the tyre and this was confirmed during evaluation of both specification tyres on the rolling drum test rig. The construction of the 2012 specification tyres does enable quicker warm-up performance, but this revised construction was not a factor in the excessive tyre heating that caused the problems experienced at Assen.”


It's gota be hard to make a tyre to suit every bike and rider ( or is that "it's gotta be hard for every rider and manufacturer to adapt to a tyre that is throw at them" ? )

It's quite possible, I suppose, that those three riders did something different to everyone else during the warm -up lap, or the first few laps.........but it doesn't seem to work for me as an explanation.


I still buy the QC theory........and it'd be no surprise to hear this type of tripe(in fact, it's a standard response) in either instance being the case.

If I sound over the top, gagging on riders and teams doesn't do much to assuage my irrational suspicions.

I smell a rat.