Bridgestone Press Release: Bridgestone Explains Assen Tire Problems

Bridgestone issued the following press release about the tire problems suffered at Assen. This evening, there will be a press debrief with Bridgestone's Manager of Motorsport Tyre Development Shinji Aoki. A full report will appear after that:

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.”


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I can't believe that there hasn't been more of an issue made of this.

If the tyre manufacturing wasn't at fault - and they're pretty adamant it wasn't - then the design of the tyres Bridgestone have produced is fundamentally flawed!

So bridgestone are telling that the riders are to blame ????
Guess someone are angry at hem now :)

Bridgestone is not saying that the riders are at fault. They are also saying that the problem was not due to some manufacturing fault.
What I understood was that they made tyres which were not adequate for the circuit. For some riders, due to their riding style and machine setup (combined with track characteristics), they overheated and chunks came out, although they were not at risk of exploding.
Apparently for Sachsenring they have different tyres and for Mugello, they will put out harder tyres.

>>Bridgestone is not saying that the riders are at fault.

They are saying the rider and crew were at fault.

>>although they were not at risk of exploding

He never said that. He said they fortunately kept their internal pressure but I'm sure Rossi and Spies' tires were not too far from catastrophic failure. When the tread chunks then the bike is riding on the carcass, a part of the tire that was never designed to directly contact the asphalt. Too much of that and I'm sure it would lose pressure with negative results.

Even if the tire didn't explode I'm sure that cornering on a tire with chunks of tread could easily lead to a serious crash. BS' lame mea copula is merely a deflection of blame as they know that since it is a spec tire series the riders have no other choice but to suck it up.

Its interesting that after all we heard from the new safety director Loris Capirossi in the preseason about making the tires safer for the riders we have not heard one word from him in response to severely damaged tires that pose a danger to riders. Its almost as if he is in that position just for some good PR for Dorna and a cushioned exit from the paddock for Loris.


It sounds to me that the tires were under-engineered (the operating range was too narrow) and 3 (2?) out of a field of 25 or so had a problem. This is prototype racing...

If I'm not mistaken, more than 2 had issues, they just weren't all severe enough to cause chunking. from what I saw watching the race, most of the tires were completely shagged on the right side.

Ok, so there was nothing faulty about the tire construction, but there WAS something faulty with the engineering. Yes, conditions were a bit different this year, but c'mon, Bridgestone should be better than that. I mean, are they on such a razor's edge that if variables stray just a bit too far the damn things fall apart?

I don't know the first thing about tire engineering and construction, so I could be totally off base here, but it seems like Bridgestone is spouting BS PR CYA speak here, instead of just owning up to producing complete crap last weekend.

If they deny they were at fault they are not apt to correct the situation.

Plus I can't believe only 3 riders had a problem. 3 riders may have had catatrophic failure but I bet many had problems. Why have different tires for each track? Any MGP tire should be able to perform at any track. Sure they could build in an advantage for some tracks but it shouldn't detract from overall performance of the tire.

Given that some 30% or more of the faster riders riders had a problem.....

I agree that this is BS culture refusing to honest and open.

Also seems like my runflats on the car - who designs road tyres that cannot be repaired.....BS!
(To be fair they are not alone of course but I wonder who's wallet they think they should be looking after.....)

Apologies for the rant....back to MGP.

Bridgestone issues their usual marketing message. The interesting point is that Bridgestone, beyond the PRspeak, is engaged in MotoGP so it can develop engineers. MotoGP is prototype racing and even though it is a "control tire" series engineers are going to experiment with every aspect of prototype tire design and construction. There are going to be errors and we learn the most from errors. That is the process of innovation. MotoGP teams know that this can influence the competition and they accept the risks as do the riders. There are times though when the "saving face" and "we are infallible" public stance of a tire supplier can slow the process of correction and punish some competitors unfairly. That is the type of hubris which harms not only the sport but the reputation of the tire company.

I don't see bridgestone experimenting or advancing anything. Some riders, like Stoner, are pretty vocal about how the tires are not only frozen tech, but in fact going backwards. They limit the tires you can use in testing, so they are obviously not there to test anything. They are there to advertise. Get the new BS tires! They blow up real good!

One day the current administration will die off and maybe we'll get our prototype racing back and tires might advance again. Until then we get fed this BullShit.

Bridgestone: "We've effectively synergized a management paradigm in order to coagulate a hemorraging leverage scenario."