Bontrager XR4 27.5x2.35in MTB tyre review
These flagship tyres from Trek’s component sub-brand are top performers in a wide range of trail conditions.
Once you’ve wrestled the relatively tight beads onto the rim, the XR4 (and all of Bontrager’s other tyres) bang into place very positively and securely once you get track-pumping.
Carcass size is ample for a 2.35in tyre and it’s taller than most so there’s a good depth of air cushioning between rim and trail. The Inner Strength sidewall protection doesn’t feel particularly tough or stable when you’re fitting it, but the XR4 handles low pressures really well with no crumpling or roll even when you’re turning in very aggressively on high-grip rock surfaces.
We’ve scored them highly in the past, but returning to these tyres the overall performance of the wide-spaced, but sloped and siped tread was still a revelation.
Whether we were flicking from berm to berm, carving fresh loam or flat-out across wet, off-camber root spreads, the XR4s stayed outstandingly surefooted and predictable, often letting us turn in tighter mid-corner than we dared hope on entry. They roll quickly enough to leave on all year and wear life is good, confirming their performance credentials.
[Editor’s note: Bontrager recently overhauled the XR4 with a new tread pattern. Stay tuned for an updated review.]