When I first bought my supra in july I had toyo tyres on the front and bridgestones on the rear (standard alloys). the weather was good for a week and I drove the car pretty hard all the time (hard not to when youve just got it ) and the grip was amazing. On the first day it rained (about a week into my soop driving) I took my fiance to work, driving carefully dropped her off, on the way home turned left at a roundabout (90 degree bend) gentle on the throttle the back end bit my head off ended up doing a 180 facing a bin lorry, went sideways up a kirb and smashed my rage front bumper what an embarresment not to mention the deposit I left in my fresh clean boxers. Anyway the next week I bought a set of 18's and put goodyear eagle F1 tyres front and back with the GS-D3 tread pattern and what a transformation, handles perfect in the dry and I tryed my best putting my foot down around bends in the soking wet and although yes the back end creeped out it was completely controllable, foot off the throttle and it corrects itself bonus
You may want to change tyres before you learn the hard way like me lol. Sorry for the long thread guys just thought I would share my experience with poor tyres and the difference a set of good tyres can make.