Indeed, tires are very complex in real life and games do little to no justice to that fact.
What I've always felt about tires in GT4 is that each car has an ideal. While some cars can run N2's with ease, other cars need something with more grip.
A good example of how distorted the tire-car relationship can be, look at the Mercedes McLaren SLR and the Amuse Carbon R. The SLR has incredible grip even though it runs more than 600hp. N2 tires can be used on the SLR without much trouble at all. On the other hand, the Amuse Carbon R doesn't have too much more power (quite a bit less weight) but when it runs N2 tires it is hopeless. In fact, the Amuse Carbon R, despite the huge wing, has such a low grip level that it doesn't really get "acceptable" traction until you're running with racing tires.
So, what this leads me to believe is that...
If you want to find the best tire for your car to ensure you will enjoy running laps, please consider using any type of tire and avoid letting stigmas change you actions.
Test as many tires as you can and stick with the one that "feels" best.
That is, unless you are running in races, then use the tire with the most appropriate level of grip and endurance. 👍
Personally, I enjoy running all of the tires, although I usually go with tires that have the most grip for their group (except with racing tires where I often choose R3s over R5s, unless I'm doing Super Race Car hotlaps!).