As we get closer to the 2022 Unbound start, it seems like everyone is launching new hoops for the unpaved roads. Shimano is going wide with their new GRX RX870 carbon wheels that have a 25mm wide internal dimension. The press release doesn't point it out but it seems like Shimano has chosen to keep a hook bead for the new gravel option. This tubeless wheelset will likely boost the volume of almost any tire. Shimano says they are for tires between 32mm to 50mm, we would say they could pair well with as small as a 28mm tire and if your bike has the room you can definitely go bigger than 50mm.