Quote Originally Posted by Mirek View Post
If I remember right it was Juho Hänninen in 2011 Monte Carlo who used it first (or at least it was first widely discussed case) when Škoda team (and Petter Solberg) fucked-up tyre choice and lost the fight for victory there. He used it out of necessity and it worked much better than let's say two winter tyres in front and two slicks in the rear.

I believe the main rationale lies in the fact that limitted-slip differential helps to bring overall grip level of the axle closer to the level of the better wheel. In that case an axle with only two wrong tyres benefits in no way from having LSD in between. Therefore if You have two better tyres it's better to place one in front and one in the rear (cross) and by that enhance a bit the grip on both axles instead of having one good and one useless.
Interesting. The cross tyre setup was a new concept for me when I joined WRC. I do recall the WRC TV commentators were discussing the merits of left-to-right mix, instead of cross. Apparently this could give them more confidence because the car will behave more predictably, albeit at different grip levels left and right.