I ran 10mm slip on spacers on track number ours times with no issues, but I run a stud and nut kit, I maybe wouldn't chance it with standard bolts? With the 10mm slip on spacer there is still a few MM of disc to sit your wheel on - remeber studs/bolts secure your wheel not the wheel centre
I could of dropped down to a 5mm spacer and still had clearance with the et35 pro race
Edit: I'm referring to 15" wheels, Carnt remeber what et trophy turinis are I'm afraid but I'm pretty sure cup turinis et38.5 clear the 280mm kit without spacers - but don't hold me to that