Track day tyres for turbo

[Eeyore9]

Going to do a couple of track days with my 996 turbo, after having some needed loving attention on suspension bits and geo set up I think I owe it to her to take her for a proper leg stretch around a couple of circuits ( with porsche club GB)
I'd prefer to don some slicks if it's sunny and have been offered a set of michelin sport cups x2 240/64/18 Fronts
x2 270/68/18 Rears are these the correct size for 18 turbo wheels? I know I have to think of the difference of ratio front to back ref awd diff and damaging it hence my question! Does anyone know a track tyre size chart specific to 996 turbo or any info for that matter? Regards

[Eeyore9]

I think this is correct that the 64 part of the 24/64/18 is 640mm unlike a road tyre which is a ratio % calculation, so the 225/40/18 road tyres are 637mm tall and that 295/30/18 is 634mm tall....
Is this within the tolerances front to back for turbo