Why would you want "track day" tyres when the standard tyre/car combination is so good? I have done a number of track days with the standard tyres and they haven't worn badly at all. The grip from these tyres is incredible - you'd have to be really driving very agressively or at an insane cornering speed to exceed the limits, even with the ESP turned off. The tyre "footprint" with such large tyre sizes is very big and the car with its four-wheel drive means that the grip levels are surely enough for anything except all-out racing?
When I got Phil Bennett (noted UK race car driver) to take me round the Nurburgring old circuit in my Gallardo I was impressed with the amount of grip and lateral G-force the car sustained on the standard tyres. Phil examined the tyres after his lap and said he was impressed with them and their lack of deterioration from his driving!
Lastly, I would think that any "track day" tyre in these sizes is going to be more expensive than the standard ones - why not just chew through a set of standards, and then replace them with another set of standards when they are worn out
William