announced a number of weeks ago that the company had founded "Stan's Racing Development division," and along with it came two quarts of SRD's first official product: "Race Sealant." The formula had been used in various forms for years, and was reportedly shipped to race teams in black, unmarked containers. Race Sealant is based upon the exact same latex fluid as the original, but it uses a mixture of large and small irregular-shaped particles that interlock more quickly and can seal fairly large punctures instantaneously. Information on the quart sized container warns that the Race Sealant must be poured into the tire directly. It cannot be injected through the valve stem and it will clog just about everything. (So, keep your valve core at 90-degrees when inflating or deflating air pressure). The official word is that Race Sealant will remain liquid as long as the original, both in the can and in the tire, and that it will function at temperatures as low as - 30 degrees F (- 34 degrees C). MSRP for a quart bottle is $39.00 USD.
After watching a local sales rep' run a ball point pen into an inflated tire a few times, I was suitably impressed that Race Sealant could patch a larger sized hole than your typical nail or cactus thorn. What impressed me more, however, was that the tire was still at a rideable pressure after two stabs with a Bic pen. At home, I mounted a pair of brand new Maxxis High Rollers, poured in 2.5 ounces into each 2.3-inch tire. (That is over one ounce less than Stan's recommended dose, but I was told by a pro race mechanic that they were using half as much of the Race Sealant and getting better results when compared with the original.) The choice of tire was because the rough bead design of the Maxxis tire makes it one of the more troublesome to mount up tubeless. Aaaaand, the High Roller was still troublesome - but less so than I can remember, and when it did pop into place, there was no bubbling at the bead interfaces, no weepy pinholes in the carcass, just a well mounted tire, ready to rock and roll.
I inflated the tires to 30 psi, using my Schwalbe digital gauge, and proceeded to punch some holes with a 16-penny nail (about 3mm diameter) - four in each wheel. After each puncture, I spun the wheel a few revolutions, but one time around was all the tire needed to seal. Afterwards, I measured the pressure and it was very close to 29 psi on both tires. I'll call that a win for normal puncture sealing. Next, I lowered the tire pressure to 20 psi (front) and 22 psi (rear) and pounded some speed runs down the rock gardens on my favorite test loop, hoping to do some sidewall damage. I managed to find two places where the sealant wept through the tire's sidewall, but there was no appreciable drop in tire pressure. The tires remained flat free ever since and typically stayed within two psi of their original inflation pressures for a number of days in storage. A check of the fluid inside the tires revealed that the sealant is behaving like the original and was not coagulating prematurely.