Adam McCullough/Shutterstock Flex Seal is a rubberized aerosol product known for its 2011 commercial featuring the company's co-inventor and co-founder Phil Swift. This commercial featured Swift removing the floorboard from a small boat, replacing it with a screen door, and spraying Flex Seal to make the area watertight. Flex Seal works on metal, concrete, glass, fabric, masonry, and plastics, but nowhere did they say the product works on rubber or synthetic rubber, despite the its rubberized coating when it dries. However, this didn't stop some zany YouTubers from broadcasting their Flex Seal experiments on passenger, tractor, and bike tires — the results of which were mixed. The makers of Flex Seal add that they don't recommend using the product on materials or situations that undergo intense heat and pressure, like gas tanks or fixing leaky radiators (the latter of which you can temporarily fix by cracking eggs). Subsequently, it's a bit perplexing seeing people use Flex Seal on tires, given that they rely on maintaining air pressure and can heat up to 195 degrees Fahrenheit. One YouTuber drilled two holes in an old tire and attempted to patch the holes using Flex Seal aerosol, letting it dry for 24 hours. The tire was filled with air and quickly began leaking at just 20 PSI. The content creator confirmed leakage by spraying soapy water on the two holes and documenting large bubbles. Think twice about using Flex Seal to repair tractor tires Zigmunds Dizgalvis/Getty Images There's a separate YouTube video where the uploader tried patching several tractor tire sidewall cracks with Flex Paste, a product in the Flex Seal family. After applying Flex Paste, the video ended, but the creator shared his results in the clip's comments. He described the outcome as being a mixed bag, noting, "The smaller cracks have been holding up, but the big one did not." Another video shows a tractor owner attempting to repair a dry-rotted tire with Flex Seal Liquid on the inner liner and bead. The content creator used a flammable gas to try to seat the tire bead on the wheel. The resulting ignition, combined with added air pressure, created sudden and intense pressure that blew out the sealant. However, the uploader noted that he didn't let the flex seal fully cure over the recommended 24 to 48-hour period. It did kind of work in bicycle and truck tires Dusanpetkovic/Getty Images A third YouTube video showed off-road aficionados using Flex Seal for a nasty gash on a 35-inch off-road tire's sidewall. The group applied flex glue that sat for three days, a coat of flex paste that cured for two days, and black liquid flex seal that dried for two days. After spraying starting fluid onto the bead and igniting it with a lighter as a seating hack, the off-road enthusiasts filled the tire with air, discovering it held. Flex tape was used to reinforce the fix, and the crew filmed a successful low-speed test. The uploader also commented that they tested the tire at 80 mph with no problems. As for bicycle tires, two content creators uploaded their video of a DIY patch, which involved spraying Flex Seal on a dilapidated tire's entire inner and outer portions. While the riders completed subsequent ramp runs, the flex seal altered the bicycle's steering feel, produced a strange sound, and a sizable hole would stretch open. These experiments show that Flex Seal can offer a temporary fix with no assurance of longer-term reliability or safety. Replace the tire if the treads are bald or have worn down to the legal limit of 2/32 of an inch, and understand which parts of a tire can be patched for the best results.