Stock wheels for the turbo models are generally 5.5 wide with an offset of ET38. They can accommodate 6.5 and 7 wide 15's although the EP82 seems very picky about the offset. If you choose a lower offset the drivers side wheel arch generally catches or scrubs on the tyre wall. The EP91 seems a bit more forgiving although given the variables nothing is gospel.
Going on previous experience I'd advise a test-fit as part of the purchase if possible. Her being an EP91 it should be grand but it's hard to be 100%.
Jay