Wow, back from the dead...
They worked out fine. I drove the car with the E90 setup for a month, then bought a new set of BF Goodrich g-Force Sport A/S tires. At that time I changed the back tires to 245/40 size which is correct for a Z3.
Drove it for 3 years/15k miles before I sold it to someone else. I never had any problems with the setup and they seemed to wear quite well. However, since I sold the car over a year ago I really can't say what it's like now.
'01 BMW 330Ci
'04 Volvo C70
'87 VW Cabriolet