Challenge Grifo PROs are the standard by which other tires are judged, ridden to countless victories over the years. Challenge Grifo’s race proven tread pattern works in all conditions, if you have one tire, this is the one. The supple SuperPoly 300TPI casing gives you precise control at low pressures and is water-resistant; no need for external sealant. CHALLENGE’s famous SEAMLESS LATEX Tube reduces rolling resistance and is protected by PPS (Puncture Protection Belt) between the tread and the casing. Removable Valve Core.