What it is: WTB's faster rolling 'trail' tire, available in fast rolling compounds with both 'Light' and 'Tough' casings, and in 2.4 or 2.6 inch widths.
Thoughts:
My interest in this tire came about due to my success with the Vigilante 2.5, which I really liked, and my interest in a larger, faster rolling tire than the DHRII I was running. The issue I was trying to overcome was the lack of tire clearance on my Smuggler, so the Aggressor 2.5 was out, as were a lot of options. At the time, WTB had a 30% off thing going on, so I ordered one to give it a shot on my Smuggler, which has notoriously tight tire clearance.
So far I've had two of these in the same compound/casing, Light/Fast Rolling. There is also a Tough/Fast Rolling, which provides a thicker casing with a ~30gr weight penalty. There is no 'High Grip' version, presumably because it would wear too quickly.
The tire mounted up in typical WTB fashion: not as easy as Maxxis, but not terribly difficult once I worked the bead out of the rim channel some.
Once inflated, I found the tire had good volume (def higher than Maxxis 2.3 options, close to the Aggressor 2.5) and cleared my frame fine.
Tread profile isn't something I really know much about, so I probably shouldn't go into much detail there. The most notable factor in the tire's profile, to me, is the flared out side knobs and the fairly 'sharp' center knobs, which seems like they'd be better suited to softer terrain than hardpack, which is fairly typical for most WTB tires.
The tire does come in fairly heavy at around 1200gr, depending on casing. The casings feel thicker than Maxxis EXO casings are, but I don't know if that translates to more durability or not. I did not have any issues with pinch flats, tears, or weeping sidewalls.
Comparison to previous versions
It is worth pointing out that the Trail Boss has undergone some recent reworks, so do not buy the previous iteration of the tire and expect the same performance. The previous WTB tires had very thin casings, low profile knobs, and less traction than the newer models.
You can differentiate, because all the newer versions are 'TriTec' rather than 'Dual DNA', also coming in different sizes.
Riding
I ran the tire near the end of a very wet winter through most of a dry, dusty summer with a few wet stretches.
I was surprised at the tire's performance in wet conditions. It is not one of the soft compound Maxxis options on the climb, that is for sure, as it will slip on wet roots and rocks a bit more, but it manages acceptably. I find it's traction in these conditions manageable, but punishing if you weight your bike wrong, essentially providing a lower margin of error on wet climbs.
The Aggressor 2.5 is a bit better in that area, but it's also higher volume and a fair bit wider.
Going downhill, I found the rolling advantage over more aggressive tires to be noticeable, but the traction difference wasn't huge unless you are comparing it to much more aggressive downhill tires. I went from a DHRII 2.3 EXO/3C to the Trail Boss 2.4 and found there was no major loss in traction except possibly a slight amount under heavy braking. It certainly can't compare to the wider downhill options out there, but they are tires for a different purpose and with a much slower rolling speed.
Despite being a fairly wet year, with a lot of muddy sections, wet roots, and other sketchy features, I found the tire would bite down under braking reasonably well and was controllable in corners. When it did break loose, it didn't seem to wildly go out of control. The added volume gives you some room to play with tire pressures, also, which can help in the wetter conditions.
I did find the tire is a bit more limited on hardpack, though, it seems like it wants to break free a bit easier than options in the same category, like the Aggressor.
So the summary is that this is a great alternative to the smaller sized DH tires, which will provide similar traction in most conditions with better rolling, however it does give up traction on steep climbs to the Aggressor 2.5 and the traction definitely isn't on par with larger DH tires (e.g. DHRII 2.4WT). Aside from riding bike parks or very wet conditions, I've found it to be one of my favorite rear tires to date, especially in softer conditions.
Wear
The main downside to the tire is the wear. After about 400 miles, you can see the difference in the tread below:
The tire still functioned fine, although it started to give up traction on wet surfaces. After around the 300 mile mark, it started to function more as a semislick, with good cornering traction but a loss in braking, climbing, and wet surface traction. There was a pretty considerable increase in rolling speed once the tire wears down some, as well.
The other rear tires I've run aren't much better, but seeing so much wear down the center of a tire at 400 miles is a slight bit more than I'm used to seeing. Especially given the majority of the riding I did was on soft dirt, it seems like this wear is a bit excessive. So who would I recommend this to?
I mostly consider this a Maxxis Aggressor alternative, I think the intention of the tire is very similar. If you are looking for a durable and fast 'enduro' rear tire, but didn't get along well with the Aggressor 2.3, this is a slightly larger version that works considerably better in every area except weight. It rolls faster, brakes better, and has more cornering traction. It's especially a good option for bikes with limited tire clearance that can't fit the Aggressor 2.5, but want a similar feeling tire.
I found on my Smuggler, which had limited tire clearance, I couldn't fit an Aggressor 2.5, so the Trail Boss 2.4 was a natural one for me to try and it worked well.
If you are expecting an all conditions enduro racing tire or one that will provide DHR2 2.4WT levels of braking traction, then it's not a good choice. I would consider the Trail Boss to be more of a trail tire and less of one that I'd run when it was very sloppy or steep, as braking traction does have limits with the tire, but it is fairly good all around on moderate terrain. It is especially good for softer dirt, but the Aggressor seems to have an edge on hardpack surfaces, both in wear and traction.
Comparisons:
vs. Aggressor 2.3 EXO : The Trail Boss 2.4 is higher volume, similar speed (possibly faster), and higher grip, however there is a weight penalty compared to the Aggressor and I think the Aggressor gets a slight nod on hardpack trails, where it feels like the Trail Boss knobs tend to bend a bit. I found tread life to be about the same.
vs. Aggressor 2.5 EXO : The larger Aggressor has slightly better climbing and braking traction, also appearing to be a little higher volume. The tires struck me as very similar, although the Trail Boss appeared to bite into loose dirt a little better and possibly is a bit faster rolling. The higher volume of the Aggressor in 2.5 from may provide more grip on wet or off camber surfaces, but at a slight rolling penalty. It's a tough call between these two and may come down to primary trail surface (hard pack vs softer ground) and availability.
vs. DHR2 2.4WT 3C/EXO : The DHR2 has more braking traction and wet weather grip, but rolls considerably slower and I find it's more effort to pedal the tire, along with rolling out of slow corners with a lot less enthusiasm. I'd run the Trail Boss for more all around trail riding, possibly dry condition enduro racing, but choose the DHR2 for steeper trails, wetter conditions, or any riding where more braking traction is justified.
vs. DHR2 2.3 3C/EXO : The 2.3 variant of the DHR2 is a bit slower than the Trail Boss, but provides slightly more braking traction. Personally, I felt the Trail Boss was better even though I had to give up a minor amount of traction, which I think probably had more to do with the compound than anything else.
Pros:
Fast rolling with reasonable traction on most surfaces
Good volume
Braking traction is decent for a faster rolling tire
Wet surface traction is surprisingly good for a harder compound tire
Thick casings provide good feel and protection
Despite fairly quick wear of the center knobs, retains reasonable levels of traction especially in corners
Cons:
Tubeless setup was slightly more difficult than other options and required moving the bead around to get it seated (YMMV depending on rim)
Heavy even in 'Light' form
Cornering traction is more limited than I'd like, if I ran it as a front tire
Center knobs wear quickly