Don't buy them unless you plan on putting 20mm spacers on front and back rims. Besides, they are used and the seller is asking $1600??!!??
According to this site:
They are style 135 for e46 M3:
Front: 18x8J, ET 47
Rear: 18x8.5J, ET 50
You are better off getting a brand new set of 260/219Mwheels and tires.
Hankook tires: $652 + shipping at Tire Rack
260M/219M wheels: (search M3 forum) or other resellers if you want 18-inch, or look for a set of 18s (real OEM style 219.) There are always some for sale in the classifieds. Price for wheels only generally ranges from $800-1000 give or take for good condition, $1100-1300 with tires.