Bontrager XR4 Team Issue Tyre

We’re becoming spoilt for choice with tyre options these days. Using the Bontrager line-up as an example, they have four different tread patterns within their cross-country line-up alone. Within each of these tread designs you can select between two or three different casing types. In total they list eleven different XC tyres which is multiplied even further by the varying width options—and that’s only the XC treads (they have separate downhill specific and gravity enduro lines).

The XR4 is Bontrager’s most aggressively treaded cross-country tyre. Most brands would probably label this an ‘enduro’ tyre but Bontrager reserves that tag for their SE4; a model that has the same tread pattern but tougher casing and tacky rubber. We looked at the $70 Team Issue model; it features a tubeless ready casing and slightly sturdier sidewalls than the $60 XR4 Expert. Bontrager also offers a heavier wire bead ‘Comp’ version that sells for $50.

Fat but Fast

Weighing in at 770g in a 27.5x2.35 size, the XR4 Team Edition offers a width-to-weight ratio that’s very competitive for a genuine full-knobby tyre. It’s a real 2.35 too; mounted to a 21mm wide rim it measured 59mm across the casing and 60mm including the tread (later I fitted it to a genuinely wide rim and it blew out impressively to measure 62mm across the casing).

The Team Issue casing was easy to mount and inflate as a sealant based tubeless tyre. We tried it with a multitude of rims and could do it with a large volume floor pump every time—furious pumping was needed with the looser fitting rim combinations but we got there by removing the valve core to speed airflow. Once inflated, the tyres held air brilliantly and top-ups were rarely needed. Overall the manufacturing quality and consistency was very good with the Team Issue tyres.

Once mounted and ready to roll, the combination of volume and tread makes for a very serious looking tyre. Despite its girth and knobby appearance, the XR4 is far from sluggish as a general trail tyre. This is in part due to the fine 120tpi casing and respectable weight; most tubeless ready tyres of comparable width are a good 100g heavier. Additionally, the XR4 is directional and the central row of blocks is ramped to improve rolling performance. It’s not an XC race or marathon tyre by any means but the combination of tread design, firm-ish compound in the centre and decent weight ensures that you won’t feel like you’re bogged down in wet cement. The opposing side of the centre blocks has a good edge to it that helps with braking traction (consider reversing the rear tyre if you want to prioritise climbing traction, but we never needed to).

Get a lean on and there’s a series of smaller intermediate blocks that take over until you have it cranked right over onto the larger, softer compound edge knobs. This along with the semi-round profile makes the tyre quite predictable. It’s not an all-or-nothing tread; you can lean it a little or a lot and it still offers something to push against. Traction-wise it can’t hold a candle to something like the Magic Mary that we’ve also reviewed in this issue, but when the XR4 does let go, it does it in a very communicative and controllable manner. Combine it with a competent handling trail bike and you’ll be feet-up drifting through the turns without needing a wardrobe change afterwards.

Conditions wise the XR4 did a great job on everything from rocky and loose trails to dry hardpack and loam. It only seemed to lose composure in the wet – the mud itself wasn’t an issue and the blocks ejected the goop well – it was more on the wet rock and roots where I felt a softer compound rubber would have been a little less like skating on ice.

Keep on Rolling

The payback comes in the form of durability. My riding combines rough and steep trails interspersed with a bit of time on the tarmac to link everything together. Prior to fitting the XR4s I was wearing tyres out at a distressing rate. The road would round off the centre knobs while the rocks would feather and hack chunks off the remaining blocks. With some of these $100 tyres only lasting a month or so, it was getting expensive. I’ve now been running the same XR4s for four months, and while the blocks are clearly rounded off, they remain intact and serviceable. If there is a weak point durability wise, it’s probably the casing. While they feature reinforced sidewalls (Bontrager calls it ‘Inner Strength’), I did manage to puncture the casing once through impacting rocks at speed. Of course there’s nothing to say I wouldn’t have damaged any other tyre in the process but the supple casing could be a little too light for some. Of course there’s always the SE4 gravity enduro version if toughness and outright traction are your number one priorities.

Sure there are grippier tyres and tougher tyres than the XR4, but finding the right tyre is always a matter of balance and compromise. I feel that this tyre strikes a really sensible balance between providing burly all-mountain traction while still being easy enough to pedal and durable enough for day-to-day trail riding.

Trek Bicycles www.bontrager.com