I dont think its a bug - those tyres are also very soft in real life, but the problem is they overheat very fast. Because your rear tyres are always cold, its just perfect
But its somehow strange, because all real life racing leagues will not allow such tyres.
Faster IRL or not, hybrids shouldn't be an option for a road car on a road course. (I'd actually like to see road-supers on the XFGTi and XRGT, but that's another story).
Dirt tyres are softer, so should be faster. I don't think there's much in it with the hybrids. I think their main benefit at the rear is that they will run at optimum on the rear of the GTi, whereas road normals run cold, so it's that which gives the most benefit.
Nah, that'd just be too boring. Having road normals on the XRG keeps it interesting, with supers you'd just be able to floor it out of corners without any thought (not that it requires much in the way of throttle modulation anyway).