When I got my car, it had Pirelli tyres on the front and Michelin on the back, the latter being rather worn. Should I replace all 4 for peace of mind?

Question from visitor, 29/12/2010 :I recently bought a used Scenic 4 wheel drive. When I got it, it had Pirelli tyres on the front and Michelin on the back, the latter being rather worn. Should I replace all 4 for peace of mind?
Answer by rezulteo, 29/12/2010 :

Even if it isn't mandatory, we advise you to equip your car with 4 tyres of the same make. You can however, have different makes on the 2 rear and 2 fronts but never mix different makes on the left and the right.