The question has more than one answer. The key is to know whether you have a puncture. The first: Removing it is the best approach. Removing it ensures the fluid and fibers mat through the depth of the rubber and cure to form a permanent bond. If the object is rigid, then it will continue to flex, risking the possibility that the bond doesn't ever set up permanently. When used as a preventative (always recommended) for hazardous tire duty, you may not know that the tire has been punctured, causing the object(s) to remain in for weeks, months, or years. A regular inspection of your tires is recommended in owner's manuals for most vehicles and equipment. Any time an object is noticed, it should be removed. The second: Some farm and ranch vehicle owners encounter thorns that are sharp but not as rigid as a nail. Thorns sometimes break off inside the depth of the rubber, leaving the leading edge protruding into the inner atmosphere of the tire. In this case, if the location is known, removing the broken off piece or pushing all the way through with a similar sized object is desired. Obviously, if the puncture isn't known about, or the location cant be found, thorns tend to flex with the tire and the sealant bonds the more flexible object to the tire making an effective seal.