I believe Pete is right, but more importantly... Are you being serious? You've bought a 370z and you're now gonna get some run flats as they have been offered to you cheap. IMO run flats will ruin the handling and performance of the car. They can't compete with normal tyres. The sidewalls are made so tough that it just makes cars horrible to drive hard. They are for lazy people.
TBH if you don't drive your car hard, then go for it. But if you do enjoy driving her with some vigour every now and then, you're gonna be so so dissappointed!!!