A fire extinguisher for automotive use is provided with the additional capability of sealing and reinflating a flat tire without any wheel removal. The device is charged with a combination fire-extinguishing and tire-sealing composition, and fitted with a removable nozzle for extinguishing fires. To seal and inflate a flat tire, the nozzle is removed, and, in its place, one end of an adaptor hose assembly is attached to the fire extinguisher, and the other end is connected to the tire valve with the wheel rotated to place the puncture or leak at the bottom. Then actuating the device dispenses sealant into the tire while inflating it, after which vehicle movement distributes the sealant and generates heat which accelerates the tire-sealing action and further inflates the tire to a higher pressure, enabling the vehicle to proceed to a service station.