The logic is that the vast majority of people can't deal with oversteer. The average driver only knows to hit the brakes when they start to get into trouble. Dealing with understeer comes naturally for those people. Let off the gas and go for the brakes and understeer pretty much goes away.
This, so if you feel you are normal listen to the salesman.
If not, and you drive thru water that the front tires push out of the way for rear tires, and can handle oversteer from cornering too fast or too much right pedal, or panic braking, put the deep tread on the front.
