Benny, I have to try and edge you away from your fixation with Preziosi and his design skills before it becomes an obsession and destroys you... or you go out there to deal with him personally
Checa did say that the bikes are designed around the tyres (apart from this year when Bridgestone decided to introduce some new ones after the bikes were designed... nice) But after he tested the GP12, if I remember rightly, he also said that Ducati's problems were caused by the tyres, not the chassis, as they had changed it X number of times with no difference in performance.
Why one bike generates heat into a tyre and another doesn't is beyond me, given the speed they all ride them at and torture they put them through. The two things that make me think there is some credence in the tyre theory is the 2009 CF bike and this year's GP12. Stoner was the only rider to ride both the GP8 and GP9 (as far as I know) and as soon as he tested the GP9 he apparently wanted it, as he felt it was a better bike than the GP8. This was sometime during 2008 so it would have been ridden on the 2008 tyres. When 2009 came around and they were on the 2009 control tyre he hit the problems they never had in testing and the only non constant were the tyres.
2012, as soon as Hayden uses the new tyre he is qualifying on the front row in Jerez and in Portugal, Rossi is finding that he once again has feel and can brake later and turn in better. OK his overall result was nothing to get heady about but the bike seemed better for him with no changes other than set up and the tyre. No mention of the chassis itself being a problem, which Rossi has said feels no different from the previous bike, just the engine putting out too much power.
So, tyres or design. Probably somewhere between the two. It will be interesting to see how the next few races develop where the bike won't have new parts but they will have a bit more experience with the new tyre and a bit of data from the new set up to work with. Will it see them noving closer to the front?