Maxxis Ardent Tire - 27.5 x 2.25 Tubeless Folding Black Dual EXOMaxxis Ardent Tire 27. 5 x 2. 25 Tubeless Folding Black Dual EXO. The Ardent is an excellent all condition tire that features fast rolling ramped center knobs with large block side knobs to provide excellent cornering traction. Ramped center knobs provide excellent traction for braking and acceleration while also reducing rolling resistance Large block side knobs provide excellent traction for secure cornering Intended use: loose loose over hard