If you are going about 25-30 mph and floor the brakes is it very likely your tires will skid and leave marks on the ground? also, right now on my 97 maxima se i have continental touring contact tires that came with it when i bought it used. how much will getting new tires like the continental extreme contact or the falken ze-512 help out in braking, handling, ride quality?

 

Slamming on your brakes at just about any speed should result in locking the wheels (non-abs). If not, it means something is wrong basically.

 

New tires are the best handling mod you can buy for your car:
http://maxmods.dyndns.org/?MaximaTires