2020 GMC Sierra Denali HD All-Mountain Review: It's a Truck on Tank Tracks, People

Tread on me.

gmc all mountain truck tank treads
Bradley Iger

“Ever driven one of these?” asks my co-driver as I settle in at the helm of the GMC Sierra Denali HD All-Mountain Concept. "Well, I've driven trucks before," I answer with a chuckle. "But this will be my first time driving one with tank treads."

In a fit of madness a few years back (and an official partnership with Vail Resorts in Colorado), GMC took a 2017 Sierra 2500 crew cab pickup, replaced its normie wheels with four tank-like tread assemblies, and dubbed it the All-Mountain. People loved it, and with the Vail relationship still going strong, GMC built a small fleet of treaded trucks out of the new-generation Sierra HD when it debuted in 2019. These are no show ponies—they're made to be driven, ostensibly up a ski slope like a fancy Sno-Cat—so drive them I will.

Bradley Iger

This particular conversion is more involved than just bolting and unbolting, though supplier Mattracks specializes in rubber tread kits designed to be that simple on certain vehicles. “Components on the front suspension are unique to this concept to make the dynamics work correctly,” explains GMC’s Mike Strickhouser. “And the folks at Mattracks supplied us with a custom set of 150 Series tracks for the project.” The Sierra HD All-Mountain is also outfitted with bits from the GMC Accessories catalog like beefed-up step bars, weatherproof floor liners, and a Sierra-branded sport bar which serves as a mount for additional LED lighting and an audio system. 

Admittedly, the end result takes the common “brodozer” crack to its logically extreme conclusion. Still, it’s an impressive sight by any measure—the additional ride height helps—and the All-Mountain’s imposing presence is boosted by both the authoritative grunt made by the 6.6-liter Duramax diesel V-8 and the telltale squeak of the tread system when the truck is in motion.

Bradley Iger

My stint with the All-Mountain concept coincided with seat time in the new 2021 Yukon at a test course laid out at the Eagle County Fairgrounds, about thirty miles west of Vail. Being confined to a controlled, mostly-flat environment is not the same thing as seeing whether the All-Mountain can bomb up a ski slope, but it's a rare opportunity to drive a bizarro OEM concept, so I'll take what I can get. 

“Just throw it into Drive and go?” I ask. My guide nods reassuringly. With that, we are off to the races. 

It’s equal parts familiar and alien, driving a rig like this. Cabin and controls don’t deviate at all from a typical Sierra HD, almost lulling you into a false sense of confidence. But the All-Mountain’s behavior in motion feels profoundly different from the moment I squeeze the throttle. The grip is a big part of it—there’s no fussing about as the four-wheel drive system crunches the numbers. You step on it, the treads grab, and it goes. Think a giant, V8-powered snowmobile and you’re getting close.

Bradley Iger

I get braver with the throttle as we proceed, pulling from a seemingly endless well of torque as we get into deeper sections of snow. It doubles as a visual spectacle—stomp the loud pedal and the treads immediately send huge rooster tails of snow skyward from all four corners. I did that a lot. 

One thing I didn’t do much of, strangely, was braking. The Mattracks retrofit adds a significant amount of resistance to the vehicle’s forward progress, akin to a purely mechanical version of the regenerative braking systems you’d find on an electric or hybrid car. Accordingly, the setup doesn’t allow you to carry momentum without constantly being on the throttle, so it really seems happiest at a tank-like pace.

Between the weight, power, grip, ride height, and finished feel, there’s a sense that this truck will climb over just about anything you point the nose at. Concept or not, it’s clear this limited exercise is just scraping the surface of the All-Mountain's abilities. Before I know it we’re back at the start of the course, where I reluctantly disembark from the treaded beast.

Bradley Iger

“It’s not headed to production,” a GMC rep jokes as I longingly watch it head back out on course. “That’s a damn shame!” I tell her. Then again, it's not like they need to—Mattracks is more than happy to outfit your truck with some treads of its own, replete with its own internal suspension system for a more civilized ride. Ridiculous, yes. But if the world is going to keep obsessing over pickups, we might as well get a little weird. It’s a safe bet you won’t see another like it in the Snowmass parking lot.