The Bontrager XR4 tire has fantastic grip even on loose dirt to the point that it is confidence inspiring. I ride the same loop consisting of 15 miles of road and 15 miles of dirt at least once a week which makes for a great testing ground for mountain bike parts, especially tires. Here’s my impression after taking the Bontrager XR4 tire out for a lap on that loop on my Ibis Mojo.
The Bontrager XR4 tire felt a little slower than other tires I’ve ridden on the pavement, probably due to the lack of center ridge down the middle. And that’s ok. At 740grams for a 262.35” tire these aren’t the tire I’d pick if you want a mountain bike tire that’s also fast on the road. For that I’d look at the Bontrager XR2 262.1”(~560g) or the Maxxis Crossmark.
Once I pointed the tires downhill I was very impressed. In corners where I’m used to other tires sliding, they held their line. I raced down one of our short, 4 minute single track descents I was able to equal my fastest time down it while feeling like I had a much larger margin for error, and much more control.
The tires profile is only slightly rounded with good size knobs fairly close together across the width of the tire, and therefore they have great grip at any angle. They accelerate and brake well when the bike is upright but also corner extremely well when leaned over. I’ve ridden other tires that have a bit of a “blind spot” (Specialized Escar, Maxxis HighRoller) meaning that if you only the get bike part way over in a corner you’ll slide or drift until you get the bike leaned over far enough to hit the shoulder knobs on the side of the tire. Not the case with the XR4. They had traction the whole time.
I’m racing the Ashland Super D this weekend and will definitely run these tires there. If you’re looking for a do everything tire for your 4”-6” travel all-mountain bike, I highly recommend the Bontrager XR4. If you’re looking for a light, fast rolling tire for XC racing, I’d say go with the Bontrager XR2.
Rolling speed: Medium
Idea use: trail riding / all mountain riding, Super-D racing
Ideal bike: 4” – 6” travel bike