Michelin has taken the highly unusual step of withdrawing not just one, but both rear tire compounds from use at the Termas de Rio Hondo circuit in Argentina. Instead, a different rear tire with a stiffer construction will be issued in the morning, with the teams being given an extra 30-minute session of warm up in which to find a set up for the tires.
The decision was taken after Scott Redding suffered a catastrophic tire delamination with the Pramac Ducati during FP4. The incident happened on a medium rear tire which had been used for just seven laps, according to a statement on the official MotoGP.com website. Redding managed to stay aboard, fortunately, but the rear of his bike was destroyed by a large strip of rubber which had detached itself from the tire. That strip of tire also hit Redding in the back, leaving a massive bruise.
The incident caused FP4 to be red-flagged, then, rather bizarrely, restarted once again, before being stopped for a second time. However, it was not immediately clear what had caused Redding's tire to self-destruct, and so the session was allowed to continue, as was qualifying. The reasoning behind allowing the session and QP to continue was that the riders would be doing only short runs, which would not stress the tire for long enough for them to become overheated.
After a meeting between Michelin, Dorna, the safety officers of the FIM, and the teams, it was decided that both rear tires would be withdrawn, as they both used the same construction. Because Michelin will only be able to pinpoint the cause of the failure after careful examination back at their base in Clermont Ferrand, France, they were not confident enough that the problem was only down to the compound, and not the construction.
Instead of the withdrawn tires, a new rear tire will be made available. The new rear features a stiffer construction, which should make it able to withstand stress on the rear better, and will use the medium compound. To allow the riders and teams extra time to find some kind of set up with the new tires, the teams will be given an extra 30-minute session of free practice, due to start at 9am local time, before the warm up sessions start. Warm up will then proceed as normal, with the race happening at the scheduled time of 4pm local time.
This is not the first time Michelin have suffered issues with the tires. Loris Baz suffered a massive blowout at Sepang during the first test, though that was later put down to a combination of low pressure and a foreign object having punctured the tire. It is worth noting that both the Baz and Redding incidents happened at tracks with extreme conditions, to the tallest and heaviest riders on the grid, both riding Ducatis, the most powerful bike on the grid.
It is also worth pointing out that Michelin did not get much of a chance to test in Argentina. The scheduled test slot was struck by poor weather conditions, Michelin and Yamaha test rider Colin Edwards spending much of his time sitting in the garage looking out. At a track like Termas de Rio Hondo, which is both abrasive and very fast, tires are already stressed. The added complication of unusually high temperatures makes life even harder for rear tires.
The one problem which is yet to be addressed is that of the weather. At the time of writing, the weather forecast for Sunday was for it to rain all day, making the extra rear slick excess to requirements. What happens if it is wet in the morning and dry in the afternoon, or wet in the morning and we have a flag-to-flag race remains up in the air.
If that happens, a decision will be taken quite late. It was precisely to handle conditions such as this that Race Direction were given the freedom to adapt the race format and strategy after the problems Bridgestone had at Phillip Island, when a newly resurfaced track was generating more heat in the rear tires than the Japanese tire manufacturer expected. Then, Race Direction shortened the race and instituted a compulsory pit stop halfway through. Clearly, that would remain an option in Argentina.