I know some on here disagree with this (Ekona ) but for me, two MPSS on the back is a shedload better than two budgets, regardless of what youre running up front. I ran for years on mismatched front and back tyres (and still was on one of my cars up till a week ago) and Ive not died yet
+1
I would also get the alignment checked, even with the best tyres it's no good unnless you make the most of the contact area