Can't be a spark plug because there are now many sizes, reaches, etc. Tires? Though I can't even find decent 165/70x13s anymore, much less the 10" or 8" I need for my micro-cars. Certainly not bulbs. Schrader valve? But not exactly on the run-flats these days, I don't think, and certainly the valve stem itself is different today. Okay, with the hint I'll go with Schrader valve.