I have just had some interesting experience with steering and tyres on a 2 litre petrol; 406 Executive model.
I have two Good Year tyres which are akin to formula one tyres, but two (not four) grooves plus, two Michelin tyres.
I had a strong pull to the right so took it into a tyre dealer who spotted that I had one Good Year and one Michelin on the front. He swapped them over (side to side) at my request and believe it or not the car then pulled to the left!
My next move was to put both the Good Years on the front. The car still pulled to the left but also now had a sort of disconcerting wobble to it.
Fed up with that, I put the Michelins on the front and the Good Years on the rear and BINGO no pulling either way and no wobble either.
In future I shall stick to Michelins and scrap the Good Years.