These are my thoughts on High ends and Sports tires from racing and driving with them.
High end tires: comes on cars like the Infernus, high end provides the most grip and acceleration, so you can hook up faster and you have can make quicker more reckless inputs, except you will get a bit of understeer with the lack of slide, on tighter turns...... And if you happen to spin out on high end tires, then it will be harder to counter and recover your car, becuase you have less time, and remember high end tires are grippy, so when your car is sideways, you cant apply power and counter steer to whip the rear end, becuase the grip will prevent that.
For example high end tires on the Comet give you more grip, better acceleration and more responsivess and since the Comet is rear engine with great turn in... so you dont get bad understeer. Overall they work great, however use caution in the rain. On a Cheetah, these just provide lots of grip, just gotta watch the understeer.
Sports tires: are in the middle of high end and and tuner. I test these on Comet and Cheetah(which comes with them stock)... They have a lil bit of wheel spin at low speed, but this is good if you want to power slide, it is very easy to peform controlled slides with these tires.
On the Comet, you can create trottle lift oversteer when you to enter a turn at high speed, lift off throttle and go into oversteer for a better exit angle, counter steer and reapply trottle rapidly, straighten up and regain grip and exit the turn at high speed.This also works on the Cheetah, generally all mid/rear engine cars behave this way.
However the Cheetah, is made for grip, and works best with High End Tires. Front engine cars like the Feltzer, have a smaller window to recover from oversteer, and the lack of weight in the rear, makes it tougher to apply throttle and regain traction to power out of the turn, but sport tires are generally the same regardless of layout. Sport tires also work well on muscle cars, expecially the Ruiner with a GT Wing.
If you car happens to oversteer, Sport tires allows for quicker and better countering and recovery. The power seems to get to the road quicker and easier. These are better in the rain, becuase of the good recovery. At high speeds there is lots of grip, and you can still slide with minimal effort if you find the need to.