I've also noticed the grip I've been getting from my tyres has decreased during the last few months. The tyres on my car are totally to blame.
I have Falkens on the front and Arrowspeeds on the back

To be fair they aren't much cop in the dry either! Was dry today and the fronts still span up under medium acceleration. I cant believe people spend circa £26k on a car an then penny pinch in tyres.
Needless to say the previous owner put these tyres on my car. She was a woman and clearly had no idea about how important tyres are! Unfortunately I can't afford to change the tyres at the mo what with Christmas. I've saved up £100 so far and hope to afford some Goodyear asymmetrics by the summer!