(Half the tires sold in the U.S. are long-haul trailer tires.) The tires have a gel-like, nonflammable, solvent-free rubber compound built into the tire’s inner liner. The gel flows into voids and around objects less than 0.25 in. in diameter, and will do this repeatedly, letting it take care of dozens of punctures. The repair gel’s yellow color highlights punctures, making them easier to see. The tires also feature four all-steel belts, which gives the tires a solid foundation for several retreadings.