Gravel bike tyres cope with the various surfaces which Gravel bikes cover - from smoother tread patterns for hard packed fast rolling surfaces to chunkier rubber for the loose & rocky routes. Gravel tyres come in 27.5 and 700c sizes and usually between 30mm and 45mm width. All-rounder tyres offer a mixed tread tread for general gravel riding. Cyclocross tyres are designed for cyclocross racing in various conditions and surfaces.