Diego,
This totally SUCKS. I'm speaking to GTB now to get something figured out for you - it's a shame that they did such a number on the wheels.
As far as the width of the wheels, to save you having to measure them, I'll make it extremely easy for you: we ONLY make 19" in 19x8.5", 19x9" and 19x10" - nothing else. Since it's obviously a rear, it can only be a 19x10"
I would check the tire specs out. Michelins (and others) come in several different specs within the same model. For example, Michelin makes the PS2 in their standard spec, in BMW spec, and in Porsche spec. The Porsche Spec PS2's (which I *think* are the N1's but I could be wrong) have less thread-ware, are lighter, stiffer, run narrower, and have a more rounded sidewall than the standard spec PS2's.
We've seen this happen more than once on several different wheels from several different manufactures. One of our customers with a 20x10" on a PS2 in 285/30/20 with standard spec is perfectly flush, and another customer with a 20x10" on a PS2 w/ Porsche spec in 285/30/20 had major tire stretch; same wheel, same tire, same size, different specs.
I would check which model of PSS the tires are first before anything else.
Hope this shines some light on the issue, and we'll work with GTB to get these babies looking like new for you
- Andy