more understeer with aftermarket tires?

[Pharmacist]

can a car's balance be affected by changing tire compound? this year i ditched the stock tires and replaced them with yokohama advan neova ad08 of the same size as the stock. i've done a couple of track days on them and i noticed, apart from the increased traction and mechanical grip, is that it seems the handling dynamics of the car changed. last year the car basically had a bit of understeer, but can easily kick the tail out with a bit of throttle. I even spun out a few times while exiting corners. This year on the new tires it seems the car understeers almost as much as a fwd car. The front tires would be squealing throughout the turn. Giving it a bit of throttle doesn't seem to break the rear loose. It's as if the rear tires have much more grip than the front. I haven't messed with the suspension at all, so that shouldn't have an effect. Can different tires really cause more understeer or is it just my imagination???????