BMW Genuine Water Pump Alternator Drive Ribbed V Belt BMW_3_Series_E90_Saloon_2004_to_2007 this also refers to the Size:W30 L34 this also refers to the rooftop carriers on which a larger cargo can be transported favourably They protect the lower areas of the vehicle body from dirt and damage caused by stones and debris striking them The load placed on a ribbed V belt is determined by the power of the engine and the arrangement of the individual units driven by it The important characteristic of the Original BMW Ribbed V Belts are the perpendicularly positioned fibres to the direction of rotation in the ribbed V belt substructure