Bontrager Gnarwhal TLR – 27.5 x 4.5 Studded Tire


It’s not very often, that we need to borrow a fat-bike to test a fat-bike tire, but it’s happened before with super fat sized tires and the litany of new wheel/hub and tire choices has created a similar situation at times. This time it was Trek’s new 27,5 fat wheel size that created the need for a demo bike to test the new Bontrager Gnarwhal 27.5 x 4.5 tires. So along with this new set of aggressive and studable tires, came a shiny orange Trek Farley 6, festooned with Bontrager flat pedals, dropper post, and a really sweet set of miniature rechargeable blinky lights. I’m going to save my thoughts about the wheel size for another time and stick to reviewing the Gnarwhal as a fat-bike tire. If you have a fat-bike with 26 inch wheels, you can change the channel, but if you ride a bike from our friends at Trek or Rocky Mountain, with those new 27.5 rims, you may be interested in reading on.


Even before we had a set of wheels or a bike to run them, we were given the opportunity to take a look at some production samples and we weighed and measured the gnew Gnarwhals. These were some of the very first sample tires that were only available for a short time. After those tires had endured a grueling schedule of guest appearances they ended up in Alaska, but we were eventually granted long term access to a set, out of the same batch of prototype production samples. Our test tires came mounted tubeless to a set of Bonty Jackalope Wheels with the studs already installed along with a handy magnetized Tire Stud Tool and 225 spare Aluminum Carbide Tire Studs, just in case I lost any during testing. Lets get to some measurements. The two tires weighed in at 1507 g and 1519 g (without studs). 218 of their studs weigh 64 g, so that puts us at 1571 – 1583 g per tire (with every available stud receptacle filled). Riders have the choice to run fewer studs to reduce weight. For comparison – A studded Dillinger 5 weighs ~ 1600 g. When laid flat the Bead to Bead was 260 mm and the tread to tread measured 124 mm. The outer stud to outer stud measurement came in at 85 mm.


The Gnarwhal is a square lugged knobby tire, that has some siping for added grip and 218 stud positions available. It’s an aggressively knobbed tire designed to give the folks that run this wheel size a choice for when conditions get rough and you need the added traction that big knobs bring to the table. The Gnarwhal joins the Hodag (low knob) and the Barbegazzi (mid-knob) family of Bontrager tires and plays both the big knobbed and studded tire roles very nicely. Let me read to you a passage from the book of Trek – “The Gnarwhal TLR is a stud-ready winter tire designed to bite into any trail surface.” The first place that I rode the gnew Gnarwhals was at the Farm that’s adjacent to Trek’s HQ. We rode some pavement and some gravel road to the trails and then rode frozen dirt on the really sweet singletrack that Trek uses as a sophisticated tool in their product development process. The tires ran great, with no sign of self steer or wobbles. Off road traction was definitely on the upper end of the scale. I even got to ride on a couple frozen puddles. These tires BITE!


So I’ve been riding this blaze orange Trek with the studded Gnarwhals for the last six or seven weeks. During that time, mother nature has thrown just about every kind of condition, for which, a tire like the Gnarwhal, should be tested. I rode in pre-winter frozen dirt. I rode during our first wet snow and two subsequent nine inch snow storms, in both groomed and un-groomed snow. We had a serious melt back that created both plate ice and crust conditions. After the last melt-back, I rode in just about, the slickest conditions that exist. Imagine a rutted and hiker pocked set of trails that has refrozen into smooth undulating plate ice; then while it’s still frozen hard, lay down just a snick of snow on top of the plate ice, with no adhesion between the new snow and the old layer of ice. Near the end of the test, the local lakes and rivers froze over and I rode across Rock Lake with the ice singing and pinging away in sort of an alien whale song. I even took them out on the beach for a big group ride called Fatter by the Lake.


The Gnarwhals are overkill on frozen dirt. Hero dirt performance isn’t what these tires were designed to to tackle. To provide you with an idea of what they were designed to tackle, let me read to you another passage from the book of Trek – “When bite and traction are required above all else this tire keeps you moving. Roll through the roughest terrain and deepest snow with the stud-ready aggressively treaded Gnarwhal.” When we enjoyed back to back nine inch snow storms, a few weeks ago, I experienced the kind of conditions that the Gnarwhal was designed to tackle. They did their job pretty well in up to about 5-6 inches of fluff. Groomed snow traction was also quite good. They float pretty well, but I feel like they’re not as float-a-licious as a Bud or a Ground Control. Tires with this much traction generally exhibit slightly more rolling resistance. Sorry for that dose of reality, but when these things are set at trail pressures, the square knobs present with moderate rolling resistance, especially on harder surfaces. Rolling resistance is a natural trade off, for added traction and bite.

Where the Gnarwhals really shine, was on the rutted ice conditions that I described above. Plate ice, with ruts from all sorts of foot and mechanized travel that would put almost any un-studded rider on their ass, was rock solid with the Gnarwhals. I rode in some really pretty sun-snow-showers that laid down about a quarter of an inch of fresh snow on top of my local ice packed trails during testing. The kind of conditions that have resulted in a couple of broken bones in my past. The Gnarwhals handled those conditions with ease and cat-like traction. Any of you that look at the stud count on these tires and think, that there might not be enough, would be mistaken. I felt every bit as stable on these tires as I do riding studded Dillingers. I have a healthy fear/respect for riding on frozen Lakes and Rivers. It really gets my adrenaline pumping to take a solo ride across a big frozen lake in the winter. I took the Gnarwhals across Rock Lake on one of the coldest days yet this winter. I stopped in the middle to take a photo (below) and as soon as I put my foot down, my un-studded boot slipped right out from under me and left me sprawled out on the ice. I hadn’t remembered to install studs on my boots. But that illustrates what a good studded tire can do in icy conditions – they BITE! These Gnarwhal TLR tires are good studded tires.


The bottom line is that the folks that made the mistake and got locked into the 27.5 fat wheel diameter now have a aggressively knobbed snow tire that has the option to be studded. That means that Farley owners have something to celebrate! The gnew Gnarwhal TLR is available now at Trek Dealers in the USA. The MSRP is $120 (unstudded). The Stud Kit with 225 studs is $50 and the handy magnetic Stud Tool is $10.

About Gomez 2576 Articles
Just an old cat that rides bikes, herds pixels, ropes gnomes and sometimes writes stories. I love a good story.


  1. Can we get a few more measurements please?
    Rim width
    Tire width when mounted on said rim

  2. Great write-up as always. The one thing I noticed about that bike when you had me ride it around the lot was them pedals! It felt like I was standing on a deck compared to my ZuZu’s. I have them on every one of my bikes. I may have to broaden my pedal horizons. My only fear would be pedal strikes, but I could probably live with a bit of that for the comfort!

  3. I tried these tires on a Bluto at our shop, it clears, but only by a paper thin margin. I would not recommend it at all. Any dirt or snow on the tire would cause immediate rubbing.

    • I’ve now had a chance to try it with studs, too. The studs scrap against the fork on the top. This tire is a definite no-go on the Bluto.

  4. How do they compare to agressive 4.8 snow tyres (bud/lou) on 100mm rims? Are they efficient in difficult snow conditions?

    • They are relatively the same in every respect, except in flotation. Bud has a slight edge in the flotation department,IMO, but it could just be that the bud is wider, while the GW is taller by 28mm.

  5. Any idea where to actually buy these? They sound great for the icy conditions we’ve been seeing lots of but I can’t find any of the 27.5s for sale.

  6. Bud is like 2.5mm wider.

    I think flotation is a wash, at best, but given the longer contact patch of the Gnarwhal, I think it’s likely more efficient on a wider range of surfaces. And *then* you factor in the studs, and it’s a big win.

  7. Stud pattern looks much improved from the 26×4″ Gnarwhal, more studs and further out. I liked the traction of the smaller tires but they lacked float and studs on the sides of the tire for, you know, turning.

    Looks like Bontrager hit it out of the park with the brew Gnarwhals!

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