Diamond-shaped file tread covers the center of the Gravel Grinder Pro, rolling quickly over hardpack dirt, broken pavement, and smooth gravel while maintaining enough edge definition to grip when climbing or braking. Challenge borrows the aggressive shoulder knobs from their Limus mud tire, spacing them wide to shed debris and provide cornering traction when you lean the bike over. The design creates a tire that feels quick on maintained surfaces but grabs when terrain deteriorates or corners tighten.

The shoulder knobs sit outside the main tread pattern, which means they don't engage during straight-line riding at moderate lean angles. You need to commit to corners before the tall knobs bite through loose material to the solid surface underneath. On shallow-angle turns at speed, the center tread handles traction duties until you lean far enough to activate the shoulder lugs. That transition point becomes predictable after a few rides, though it requires more attention than tires with progressive tread designs.

Handmade construction applies natural latex coatings to the 260 TPI Super Polyester casing before the SMART Plus compound tread gets glued in place. The process creates a supple tire that deforms over rough terrain rather than bouncing, though the porous casing requires more sealant than vulcanized alternatives. Expect to use 60-90ml of sealant per tire initially, with regular top-ups to maintain proper sealing. The sidewalls weep sealant during the first few weeks until the latex coating saturates fully.... Read More