By Jon Crowley
For this Yamaha RMAX4 rock crawling review, I took the 2025 Yamaha Wolverine RMAX4 1000 onto Double Sammy at Sand Hollow State Park in Utah. The goal was to find out how well Yamaha’s redesigned four-seat trail machine could handle technical rock crawling in mostly stock form.
The RMAX4 was designed first and foremost as a comfortable, versatile trail UTV capable of carrying four adults. That makes its performance on a difficult rock-crawling trail particularly interesting. A good recreational side-by-side should be able to handle the unexpected obstacles that appear during a family trail ride—even if it was not developed as a dedicated crawler.
What Changed for the 2025 Yamaha RMAX4?
The redesigned 2025 Yamaha Wolverine RMAX4 1000 introduced a longer wheelbase, a full-size rear passenger compartment and several updates that improve its versatility on the trail. Important changes and features include:
- Longer wheelbase and updated chassis: The redesigned platform provides a more spacious rear cabin while giving the RMAX4 a stable, planted feel on steep and uneven terrain.
- Updated On-Command 4WD: Yamaha improved front differential engagement and disengagement. The system offers 2WD, 4WD and 4WD with differential lock, along with Turf Mode for unlocking the rear differential when appropriate.
- Selectable electric power steering: Drivers can choose High, Standard or Low steering-assist settings. Yamaha also provides an additional steering map when the front differential is locked.
- Revised suspension calibration: Updated spring and damping settings improve control and ride quality across a wide range of terrain.
- FOX iQS suspension: The Limited model allows the driver to adjust the suspension electronically to suit changing trail conditions.
- Full-size rear seating: Adult rear passengers gain more legroom and easier access through full-length rear doors.
- Adventure Pro and rearview camera: The Limited model’s integrated seven-inch display includes vehicle information and an automatically activated rearview camera.
For a complete overview of the redesigned machine, see our 2025 Yamaha Wolverine RMAX4 1000 introduction. We also covered its comfort, suspension, handling and performance during our 2025 Yamaha RMAX4 1000 first-drive review at the San Rafael Swell.
Testing the RMAX4 on Double Sammy
After driving the RMAX4 at Yamaha’s San Rafael Swell media ride, I wanted to see how versatile the new platform really was. I took a demo unit to Sand Hollow and headed for Double Sammy, one of the area’s best-known technical trails.
Double Sammy is rated 7 and measures only about 1.8 miles, but the trail packs numerous ledges, steep climbs, off-camber sections and closely spaced obstacles into that short distance. It provides a meaningful test of a UTV’s traction, gearing, clearance and low-speed control.
Three Things I Evaluate in a Rock-Crawling UTV
When evaluating a UTV for technical rock crawling, I pay particular attention to three areas:
- Front differential-lock performance: The locker needs to engage predictably and provide dependable four-wheel traction.
- Low-range gearing and clutch control: Technical terrain requires controlled power delivery without excessive speed or unnecessary belt slip.
- Tire clearance and ground clearance: Larger tires can improve breakover clearance and traction, but only if the chassis and suspension provide enough room.
Yamaha RMAX4 Rock Crawling Video
Clutch and Low-Range Performance
The RMAX4’s Ultramatic transmission was one of the strongest parts of the test. Yamaha uses a centrifugal clutch that maintains constant belt tension, and I did not experience belt slip while working through the obstacles on Double Sammy.
Low range felt somewhat tall for slow, technical crawling. That required more attention to throttle control than I would prefer in a purpose-built rock crawler. Even so, the clutch system performed extremely well and delivered consistent power without giving me concerns about the belt.
Front Differential Lock and Steering
The updated On-Command system engaged and disengaged the front differential lock quickly and predictably. Once locked, the RMAX4 generated the traction needed to climb ledges and maintain momentum through uneven obstacles.
Selectable electric power steering is another useful feature. The High, Standard and Low settings let the driver tailor steering assistance to the terrain, while the dedicated differential-lock steering map helps manage the additional steering effort that normally comes with a locked front end.
Suspension and Chassis Control
The RMAX4 suspension package worked exceptionally well. Its longer chassis felt stable on steep climbs, and the suspension kept the machine composed as individual tires climbed ledges or dropped into holes. The FOX iQS system on the Limited model is especially helpful because the driver can change suspension settings without leaving the cab.
The rearview camera also proved more useful than it may sound. On a long four-seat machine, being able to see what is immediately behind the vehicle can help when repositioning or backing away from an obstacle.
Tire Size Is the Biggest Limitation
The stock RMAX4 comes with 30-inch Maxxis Carnivore tires. They provide good all-around traction, but the amount of room available for substantially larger tires is limited in stock form.
A 31-inch tire is a realistic upgrade. Some 32-inch combinations may appear to fit, but clearance can become tight at the rear when the suspension reaches full compression. That limitation affects both ground clearance and the RMAX4’s ability to roll over larger ledges.
Owners who want larger tires can address the limitation with SuperATV high-clearance 1.5-inch forward-offset A-arms for the Yamaha Wolverine RMAX 1000. SuperATV says the arms provide clearance for tires up to 34 inches while moving the front wheels forward 1.5 inches.
What the Yamaha RMAX4 Does Well
- Excellent centrifugal clutch performance with no belt slip during our test
- Quick and predictable front differential-lock engagement
- Three selectable power-steering settings
- Additional steering assistance in differential lock
- Well-controlled suspension on uneven terrain
- Driver-adjustable FOX iQS suspension on the Limited model
- Stable chassis and good passenger comfort
- Useful rearview camera
Where the RMAX4 Could Be Better
- Stock tire clearance limits practical tire-size upgrades
- Low-range gearing feels tall for slow, technical rock crawling
- The long four-seat chassis requires careful line selection on tight obstacles
Yamaha RMAX4 Rock Crawling Review Verdict
The Yamaha Wolverine RMAX4 1000 is not the best purpose-built rock crawler straight from the showroom, but that should not be surprising. Yamaha designed it as a versatile four-seat trail machine capable of carrying adults comfortably while handling a broad range of terrain.
Within that mission, the RMAX4 performed impressively on Double Sammy. Its centrifugal clutch, dependable front differential lock, strong power steering and excellent suspension gave me confidence throughout the trail. The biggest restriction is tire clearance, while the relatively tall low range requires more deliberate throttle control in difficult terrain.
If I were buying an RMAX4 primarily for trail riding and occasionally encountered technical rock-crawling obstacles, I would be comfortable relying on it. Owners who expect to crawl regularly should consider additional tire clearance, underbody protection and a carefully chosen tire upgrade.
