Borrowing the same tech as their XC version, the Vittoria Air-Liner Light Gravel tire insert weighs virtually nothing and uses a semi-permeable foam that expands if you puncture to fill the tire so you can keep rolling.
The material absorbs the air you inflate into the tire, slowly (over about 8 hours) equalizing the air pressure inside the foam’s air pockets and your tire. Then, if you puncture and the air rushes out of your tire, that pressure drop causes the air trapped inside the foam to expand and partially fill the tire.
Vittoria says it’s enough to let you keep riding…for a while, anyway. Unlike XC, where it could be enough for you to finish a lap (or even a complete race), with gravel it could be enough to get you to the next aid station where you can perform a proper fix. Or, if you’re plugging the tire road side, it means you won’t have to mini-pump as much air back into it to get rolling again.
It also adds a quasi-suspension effect, helping support the tire at lower pressures and preventing pinch flats. I’ve been riding it on my XC bike and they’re nothing short of amazing – so much so that I gave them my Editor’s Choice award last year.
Retail is $69.99 per tire, weight is 40-45g depending on size. They’re designed for tubeless gravel tires ranging from 42-50mm wide mounted on rims with 23-25mm interior widths. Available in 650B and 700c diameters.