In karting, grooved tires for wet weather are called wets.
Wets are designed for rain-soaked tracks. Their molded grooves channel water away from the contact patch, helping the rubber remain in contact with the asphalt instead of riding on a film of water. Kart wets are also made from softer compounds than dry-weather slicks, which helps them generate grip and heat in slippery conditions.
The main mix-up is with slicks. Slick tires have no tread grooves and are intended for dry tracks, where their uninterrupted rubber surface provides maximum grip. “Rain tires” and “wet tires” are broader names for the same wet-weather category; in karting, “wets” is the familiar short form. “Cuts” can refer to modified slicks used in some dirt-track applications, while spiked tires are specialized for icy conditions.
Wets are not automatically faster whenever the track is damp. On a drying circuit, their soft rubber can overheat and wear quickly, so drivers generally switch back to slicks when enough dry racing line appears.