TWO WIDTH OPTIONS for Gravel Bike Adventures – The WTB Riddler offers both a 45mm gravel bike tire for rugged terrain and bikepacking, and a 37mm tire for faster, lighter cyclocross and speed-focused gravel riding. Optimize your ride with the perfect width for your needs. ICONIC TAN SIDEWALL COMFORTABLE 60tpi Construction - The Riddler 45 and 37 in 60tpi casings are constructed with more rubber and provide greater protection and comfort than other thin casing gravel tires. When setup tubeless the plush casing provides a vibration damping effect on the bumpiest of roads. TUBELESS READY for Better Gravel Bike Traction – The Riddler tire’s Tubeless Compatible System (TCS) allows you to run lower tire pressures for enhanced traction, a must-have for gravel bikepacking and off-road adventures. Fewer flats, more traction, and more confidence. SEMI-SLICK TREAD for Fast Rolling Efficiency – This WTB gravel bike tire features a semi-slick center tread for reduced rolling resistance and raised knobs for cornering traction. The 45mm version shines on rough gravel, while the 37mm is perfect for dry cyclocross courses.