M as in motorsport. For an even racier Z4 Coupé: 18-inch double spoke 135M wheels (8 J x 18 alloy wheels with 225/40 R18 tyres at the front; 8.5 J x 18 alloy wheels with 255/35 R18 tyres at the rear). BMW alloy wheels are subjected to rigorous real-world testing before going into production, ensuring they function perfectly and meet the highest standards of quality.
