Bontrager's fat bike tires have cool names like 'Gnarwhal' and 'Barbagezi', but unfortunately the rest of their mountain bike tires don't get the mythical creature treatment. Instead, there are two letters and a number that designates the casing type and how aggressive the tread pattern is – it's like the Dewey Decimal System for tires.
Take the SE4 tires reviewed here. The SE initials signify that they have Bontrager's Core Strength Casing, which has extra reinforcement at the sidewalls and under the tread to prevent punctures. It's thicker, and a little heavier than Bontrager's more cross-country oriented XR casing. The number 4 in the SE4's name is out of 5, which places it on the more aggressive side of the spectrum, with a tread pattern designed for a wide range of conditions, from hardpack to loose, and wet to dry.
Bontrager SE4 Tire Details
• 61a / 50a dual rubber compound
• Tubeless ready
• Core Strength casing reinforcement
• Sizes: 27.5 x 2.4, 2.6, 2.8"; 29 x 2.4, 2.6, 3.0"
• Weight: 1070 grams (29 x 2.6")
• MSRP: $84.99 USD
Plus-tires didn't quite live up to the hype that surrounded their introduction, but over the last year or so we've seen numerous 2.6” options hit the market, part of what seems like an attempt to find the Goldilocks width, one that provides plenty of traction and compliance without the vague handling and delicate sidewalls of the original Plus tires. There are 2.6” and 2.4” versions of the SE4 for both 27.5” and 29” wheels, along with a 29 x 3.0” option and a 27.5 x 2.8” option. MSRP and weights vary, but a 29 x 2.6” tire weighed in at 1070 grams and retails for $84.99 USD. Performance
The SE4 tires mounted tubeless up without any trouble on a rim with an internal measurement of 28mm. That number is a smidge narrower than the ideal range of 30-35mm for a tire this wide, but it didn't pose any issues out on the trail. As far as the actual tire width goes, the SE4 measured true to size – at 20 psi the casing measured 2.5” and the distance from side knob to side knob was 2.6”. It's good to see that Bontrager's calipers are properly calibrated – I've run into a few tires from other brands that say 2.6” on the hot patch, but measure barely 2.4” wide at a useable pressure. On the topic of pressure, I typically ran 20 psi in the front and 22 in the rear, and a pound or two less for wetter days when I wanted as much grip as possible.
On the trail, the SE4 was a very easy tire to get along with. It doesn't have the most aggressive tread pattern out there, but it offered up plenty of traction for the dry and dusty summer time riding here in the Pacific Northwest. It's no slouch in the wet either, as long as it's not too muddy – there aren't any super tall knobs to slide out suddenly on roots or rocks, which makes it easy to predict how it'll behave even when the trail is covered in a layer of slime.
The overall profile is more round than square, which creates a very predictable transition onto the side knobs when cornering, and those side knobs are well supported to avoid any unwanted squirming. It rolls smoothly, and feels noticeably quicker than a more aggressively treaded tire like a Schwalbe Magic Mary or Maxxis Minion. Of course, the tradeoff for that extra speed is that it doesn't dig into the ground quite as tenaciously as those two aforementioned tires, but it still does well on all but the steepest and sloppiest of trails.
The 2.6” width goes a long way toward smoothing out chattery sections of trail – the SE4 is an excellent choice for a hardtail or shorter travel bike where the extra cushioning provided by the higher volume casing is especially helpful. The one downside to the extra width is that the tires can feel a little 'floaty' in looser, conditions, especially if the trail is steep – in that type of situation they weren't able to dig in and bite quite as well as a narrower tire with taller knobs would.
When it comes to durability, I haven't had any punctures so far (knock on wood), and the tread wear is very even and more than reasonable considering the number of miles I have on them.Pinkbike's Take