BMW has chosen the Michelin Pilot Sport 4S (PS4S) tyres as a 21-inch summer tyre fitment for its new high-performance X3 M and X4 M models. According to company, the new BMW X3 M and X4 M Competition models, which are fitted with 21-inch light alloy wheels, will be equipped with Michelin PS4S 255/40ZR21 102Y front and 265/40ZR21 105Y rear ultra-high-performance tyres.