The 303 XPLR SW is big enough for your biggest gravel goals. Super-fast on gravel thanks to its mega-wide rim profile and utilizes Zipp's Total System Efficiency specifically to the challenges of gravel. The wide profile increases air volume, allowing for lower tire pressures without squirm. That means riders can mitigate surface vibrations while maintaining grip when cornering or traction while climbing. The rim profile also creates a seamless transition with gravel tires for unsurpassed aero efficiency on gravel. And while the 303 XPLR SW is built big, it's still lightweight to keep you fast and fresh for those long, fulfilling days in the saddle.UD Carbon fiber with ABLC surface Dimples, tubeless and hookless rim construction: 32mm width and 54mm depth profileWide and deep profile integrates seamlessly with gravel tires to increase aerodynamic efficiencyCX-Ray spokes with aluminum nipples, carbon steel cartridge bearingsApplies Zipp s Total System Efficiency to high-performance gravelZR1 Center-Lock disc hub with better seal design for improved durability, and 6 pawls with compression springs for 66 points of responsive engagementDesigned for Zipp approved, compatible tires onlyMax tire pressure 50 psi, with the ability to run pressures under 30 psiItem SpecificationsCassette Body TypeShimano HG 11/12-Speed RoadColorCarbonDefined ColorCarbonHub/Brake CompatibilityCenter-Lock DiscISO Diameter622 / Road / 29"Rear Axle12mm Thru x 142mmRim MaterialCarbonRim Width (Internal)32Tire TypeTubeless ReadyValvePrestaWheel Size700c Zipp 303 XPLR SW Rear Wheel Rear Wheel UPC: 710845901447