Review by Fred Robinson // Photos by Ian Collins
Claiming it will “out-corner any XC tire on the market,” Bontrager sounds pretty confident in their XR4 Team Issue tire. With an aggressive tread pattern on a relatively lightweight tire, it's fair to assume Bontrager is targeting the Enduro crowd with the XR4, aiming it more specifically at those who enjoy riding their trail-bike more like a mini-downhill bike than an XC bike. We put it to the test to see just how it stacks up.
XR4 Team Issue Tire Highlights
- Bold and aggressive tread pattern
- Excels in loose and rocky conditions
- Tubeless ready (TLR) - Tire is ready to accept self-sealing TLR Sealant as the final step in a worry-free, tubeless setup
- Inner Strength Casing - Lightweight sidewall protection is supple and strong
- Unconditional Bontrager Guarantee
- Available in 26, 27.5, and 29-inch versions
- Weight: 582 - 790 grams
- MSRP $69.99 USD
Upon first inspection we were happy to see that the XR4 tires were a bit meatier and more aggressive looking than some other XC/Enduro branded tires out there; and surprisingly, they weigh in at a reasonable 780 grams for the 27.5 x 2.35 - not too shabby. The XR4 is a tubeless ready (TLR) tire and we were able to mount it up as such with only a floor pump and Bontrager's TLR tire sealant. Once mounted on the bike we realized that the XR4 is a fairly wide tire, on par with our Maxxis 2.5” DH tires.
On The Trail
The large volume of these tires is one of the first things we noticed when we first tested them out on the trail. We started with our typical 35psi rear and 30psi front, but at these pressures the tire deflected off rocks too much and had poor feel as far as trail feedback went. After taking it down to 30psi rear and 27.5psi front, the XR4 felt about right for most trail conditions. At this pressure (and given our body weight), the tire would give a bit on hard, square-edge rock strikes without deflecting while still holding enough air to prevent rim strikes. This pressure also seemed like the sweet-spot for cornering (again, for our body weight); not low-pressure squirmy, yet able to hook up well in corners. Bontrager recommends 30-50psi for the XR4 in the 27.5 x 2.35 configuration depending on body weight but we found that to be a bit high. Being on the larger side for a typical mountain biker, using Bontrager's guidelines we should have been running 50psi and that would be flat out scary.
In the past, we were not huge fans of most tires with intermediate knobs between the center and shoulder knobs, and initially this was a concern in regards to cornering performance. But, once we found our ideal tire pressure, cornering traction proved to be great. These things hook up like our favorite DH tire and have a predictable break-away point that you have to actually push a bit harder to get to than we were used to. Braking traction was great too, but where these tires due suffer a bit is in the rolling resistance department. We found the XR4 to roll a bit slower than some other XC / Enduro branded tires. This is far from a deal breaker though as this tire seems to excel in most other categories.
We got to ride these tires in a variety of different conditions, from sloppy mud and snow to SoCal desert hardpack and the tire performed well throughout. It shed mud very well in conditions where we noticed our buddies tires caking up with dirt. Climbing traction was good in loose, dry conditions and despite rolling a bit slower than other offerings the tires never felt outright sluggish.
Long Term Durability
So far the XR4's are wearing great. With about three months of regular use there is hardly any noticeable wear, no torn side-knobs, and no excessive wear to the braking edge of the knobs either. In the past we've gone through quite a few single-ply tires from cuts on the sidewalls but so far the XR4 has proved resilient and durable even after charging some sharp, pointy rock sections.
Things That Could Be Improved
One gripe is the XR4's rolling performance, but given the trend of people building burlier, so-called “downhiller's trail-bikes,” there is definitely a market for the XR4 as a slower rolling but more up-for-it general trail tire.
Additionally, flat protection when running the tire with tubes leaves something to be desired. Flats seem to be too common of an occurrence set up that way. Set up tubeless, on the other hand, they have been quite reliable.
What's The Bottom Line?
Bontrager's on a roll, and this time they're using the XR4 tire to keep up their momentum. The XR4 would be a great option for the trail rider who wants a slightly burlier tire without a big weight penalty. If the somewhat higher rolling resistance is a deal breaker for you, the XR4 would make an excellent front-specific tire paired with a faster rolling tire for the rear. We were happy running it front and rear though and found the overall performance of the XR4 tire to be excellent.
For more details, visit www.bontrager.com.
About The Reviewer
Fred Robinson, a.k.a. "Derf," has been on two wheels since he was two years old. He picked up a mountain bike in 2004 and started racing downhill in 2006. He has seen moderate success racing CAT 1 but focuses his efforts on building, maintaining and riding his local trails. He's deceptively quick for a bigger guy and likes steep, fast trails where he can hang it off the back of the bike. As a SoCal native he mostly rides trails covered with loose, traction-less turns and sharp, immovable rocks. Besides downhill, he rides trail bikes, road, and also enjoys the occasional dirt jump session. He is currently a student at UCSD and a wrench at a local bike shop.