The Donnelly X'Plor MSO tire design is a shout out to the Adventure Cycling Association, headquartered in Missoula, Montana. Hence the airport code, MSO, for the tire designation. Developed with the needs and requirements of adventure cycling, the X'Plor MSO Clincher Tire is a large volume, highly versatile option for adventure, all-road/gravel, commuting, and specific cyclocross riding. The fast rolling design has surprising hook-up in mixed surface riding.

The tread pattern is the first reason the MSO jumps out at you. While it looks fast rolling and somewhat solid in the center, a closer look reveals directional vector knob clusters and shapes that do roll fast and pretty smoothly on pavement, but have slight separations and incuts that ensure grip on hard, slick surfaces, such as dusty or wet rocks. Just off the center on both sides are a one-one series of small and larger hexagonal knobs that pitched front to rear. These knobs carry your grip and consistent feel off the center when cornering, offering stability on pavement and grip off-pavement. The top of the shoulder/edge features a combination of the same larger hexagon of the inner line, but is offset with a small triangular knob, that points to the centerline. Again, here is your cornering transition, but with slightly more open space, also a source of traction in softer terrain, especially at lower pressures.

The pure edge tread line is a story in itself. There is a tandem knobset, with a flat edge, five sided, smaller forward tread paired with a larger, mirrored version of the same shape, but which has a beveled top surface that is higher in the rear. Between the mirrored pair, in sequence, are two smaller hexagonal knobs with more space in between. This design is for enhanced grip, stability, and traction, especially in off-road or trail riding situations where softer, or loose material can get sketchy, and despite the fact that this tire says "fast rolling" the hook-up is excellent and confidence inducing. A brilliant tread design all around.

There is suppleness that suggests a flexible casing material, with the 60 TPI design delivering the right combination of feel and strength an all-rounder needs. The folding clincher bead secures on all hooked clincher and most tubeless ready hooked clincher rims. The surface and tread rubber is a Shore 70A hardness, which offers good wear, lower rolling resistance, and overall durability. Grip is largely a function of the tread pattern and tire footprint, so the tire pressure you choose will be driven by conditions and terrain.