I have loaded wheels with 2.6" tyres without any problems. The description even says that " Extra long rim retaining straps with ratchet function allow easy attachment of wheels (wheel width up to 4.7"), enabling the transport of fatbikes". The storage box is not included

Just loaded: Cube Stereo Hybrid XL with 27.5" wheels and wide Schwalbe Hans Dampf tyres (2.6 I think). Fits straight but well, the supplied rim retaining straps are just long enough. You can also buy longer straps.