Fresh spy shots just pulled the curtain back on what might be the most aggressive half-ton truck General Motors has ever built. The 2027 Sierra AT4X was caught wearing thinner camouflage than ever, and what’s underneath looks like a direct shot at the Ford Raptor and Ram 1500 RHO.
I’ve been tracking GM’s next-gen truck prototypes for months, and this is the first time the off-road flagship has shown this much skin. The details are stacking up fast, and some of them caught me completely off guard.
At a glance
| Spec | Detail |
|---|---|
| Model | 2027 GMC Sierra 1500 AT4X |
| Tires | 35-inch Goodyear Wrangler Territory MT on 18-inch wheels |
| Suspension | Multimatic DSSV dampers with 2-inch factory lift |
| Engine | New-gen small-block V8, larger than outgoing 6.2L |
| Key upgrade | Aggressive front bumper cut-outs, first for AT4X |
| Expected reveal | Summer 2026, standalone event |
| Estimated price | $75,000+ based on current AT4X pricing |
Why 35-inch tires change the entire equation
The outgoing AT4X rolled on 33-inch rubber. That extra 2 inches of tire diameter sounds modest on paper, but in practice it transforms what a truck can do on a trail. Larger tires clear bigger rocks and ruts, and when you air them down for crawling, the additional sidewall flex keeps the bead seated on the wheel while spreading a wider contact patch across loose terrain.
GMC went with Goodyear Wrangler Territory MTs, which are proper mud-terrains rather than the all-terrain compromise tires you see on most factory off-roaders. The Ford Raptor still ships with 35s as well, but the Ram RHO tops out at 33-inch BF Goodrich KO2s from the factory. That gap matters when you’re stacking your truck against the competition at a trailhead.
What GMC isn’t saying about that bulging hood
Two massive power bulges sit on top of the hood, and GM insists they’re not for engine clearance. I think the real story is what’s going underneath them. GM’s next-generation small-block V8 is expected to exceed the current 6.2-liter in both displacement and output. The outgoing 6.2 makes 420 horsepower. If the new engine pushes past 450, the AT4X suddenly has a power argument against the Raptor’s 450-hp twin-turbo V6.
The hood bulges also serve a visual purpose that lines up with the rest of the truck’s new attitude. The fender flares are boxier and more squared-off, borrowing the heavy-duty look from the Sierra HD. Reflectors integrated into the flares mirror what you see on the current 2500 and 3500 models. GMC is clearly trying to make the half-ton look like it belongs in the same conversation as its bigger siblings.
The one catch nobody is talking about
Look at the rear bumper area in the spy shots and you’ll notice something missing. There are no rear tow hooks. The current AT4X has them, so their absence here is deliberate. My read is that GMC is holding rear recovery hardware for a possible AEV Bison edition, the way it does with the current generation. That means the base AT4X might lose a feature some owners actually use on the trail.
The front skid plate looks substantially beefier than before, and additional underbody armor covers vulnerable components underneath. The exhaust exits are tucked almost entirely inside the rear bumper, which improves departure angles on steep descents. Ahead of the bumper, the exhaust routing sits higher than the full-size spare tire. These are details that matter when you’re actually wheeling the truck and not just parking it at a brewery.
Ford and Ram should be reading these spy shots carefully
The front bumper now features aggressive cut-outs ahead of the front tires, a design GM has used on Chevrolet ZR2 models but never on the AT4X. These cut-outs let you place a tire on a rock or log without smashing the bumper first. It sounds like a small thing until you’ve watched someone crack a $3,000 bumper cover on a moderate trail obstacle.
The Multimatic DSSV dampers are back, visible poking through the wheel arches. These spool-valve shocks remain the gold standard in factory off-road suspension. They manage body control across everything from highway cruising to high-speed desert running to slow technical crawling. Neither Ford’s Fox Live Valve shocks on the Raptor nor Ram’s Bilstein units on the RHO have matched the DSSV’s range in independent testing.
How it stacks up
| Model | Factory tires | Suspension | Est. power | Edge |
|---|---|---|---|---|
| 2027 GMC Sierra AT4X | 35-inch MT | Multimatic DSSV | 450+ hp (est.) | Best dampers, mud-terrain tires |
| 2026 Ford F-150 Raptor | 35-inch AT | Fox Live Valve | 450 hp | Proven desert runner |
| 2026 Ram 1500 RHO | 33-inch AT | Bilstein | 540 hp | Raw power advantage |
| 2026 Toyota Tundra TRD Pro | 33-inch AT | Fox internal bypass | 437 hp (hybrid) | Hybrid torque |
Why this matters
- GM is closing the tire and armor gap with Ford’s Raptor
- A bigger V8 signals the horsepower war isn’t slowing down
- Summer 2026 reveal puts pressure on Ram and Toyota timelines
The verdict
The 2027 Sierra AT4X looks like GMC finally building the truck the AT4X badge always promised. Bigger tires, a more powerful V8, and trail-focused bumper design put it in direct competition with the Raptor in ways the outgoing model never quite managed. If GM prices it under $78,000, Ford has a serious problem on its hands. The off-road half-ton segment is about to get a lot more interesting, and GMC is the one forcing the conversation.
I’d keep a close eye on GM’s announcements this summer. If you’re cross-shopping a Raptor or RHO right now, it might be worth waiting a few months to see what GMC officially puts on the table. This is shaping up to be one of the most competitive off-road truck launches in years, and locking in a purchase before all the cards are revealed could mean leaving the best option on the dealer lot.
