Michelin won't be building Rossi a tire to suit him. I'm sure they're salty after he wanted to leave in 2007.
I'm sure Michelin still remember this, but it seems their tires weren't good by 2007.
Also the reason in 2008, Rossi began performing better is because MotoGp is a battle of engine architects, and only one shall win because that's how formula racing works,
in my opinion. Someone comes up with a good idea and everyone else has to copy. When the 4 strokes were introduced in 2002, I picked back that the V5 will win when discussing this amongst my friends. It sports more advantages than the I4... currently there is no evidence that Honda and Ducati have ever explored the I4 whereas according to Burgess Yamaha has explored the V4...
Paraprasing Jeremy Burgess as I can't find the direct link:
".....when working at Yamaha last year they would like to build a V4 engine but there is too much instability in the regulations at the moment and they don't have the man power to develop a new engine"
Paraprasing Neil Spalding on Cooling... as I can't find the direct link:
"Yamaha M1 is the hardest MotoGp bike to cool. Compared with the narrow V4s and the old V5s, its across the frame four reduces airflow through a large area of radiator, and forces the of narrow exhaust ducts."
*This gave Yamaha a lot of trouble in the 990 years, particularly when their M1 got stuck in the hot, turbulent wake of another bike. Rossi famously crashed a Sachsenring in 2007, desperate to get past De Puniet and into some cool, undisturbed air."
"It was only the arrival of Bridgestones tyres in 2008 that saved the situation when Yamaha adapted by moving their engine back in the frame, they got more room for the radiator and the ducts that shoveled its hot air away"