NO NO NO NO NO  DO NOT SLASH BUS TIRES!     Truck tires are pumped sometimes well over 100 psi.  Trying to knife a truck tire will blast your arm off, literally. Its about as bad a puncturing a scuba tank.  They need that extreme pressure so they don't much under the insane weight of buses and trucks.    Let the air out of the tires, THEN slash them or cut the brake lines.