noun which may take the genitive case particle 'no'
four-wheeled
Used attributively to describe vehicles or objects with four wheels. Often appears in compounds like 四輪車 (four-wheeled vehicle).
Four-wheel-drive cars handle well on snowy roads.
He drove a four-wheeled buggy across the desert.
三輪 refers to something with three wheels (like a tricycle), while 四輪 refers to a four-wheeled vehicle (like a car), so the two are easily confused when discussing wheel count.
Compound of 四 (four) and 輪 (wheel). The reading よんりん follows standard on'yomi.