I thought it it the proper place to ask such questions, so look at this website: http://www.mgf.ultimatemg.com/group2/su ... _angle.htm
It says: What changes a slip angle into a slide angle? Excessive slip angles!!! That is, a slip angle is so called because the part of the contact patch that is to the outside of your turn is moving faster than the wheel itself is in the direction it (the contact patch) is pointing while the part on the inside is moving more slowly. (Exactly like camber thrust.) Since the outside part is moving faster than the tyre it must be slipping. The inside part is gripping better than it would if moving in a straight line. For this reason the contact patch 'walks' itself into the turn.
I thought otherwise, as when taking a turn, the tyre gets deformed in such a way that the vertical weight transfer of the car to the ground is limited if there's nothing over it; the normal force should be higher over the yellow area http://imageshack.us/photo/my-images/822/kbz12.jpg