Actually, for the most part, the F-250 handled this load like it wasn't there. Clearly, there was plenty of power. Our test route took us up the 4190-foot Cajon Pass, a section of Interstate 15 between Los Angeles and Las Vegas known for wind and heat. It's a long pass, with heavily trafficked truck lanes. We towed at a steady 60-65 mph into oehigh-profile truck wind warnings. On those occasions when we had to make way for a big-rig to pass a slow-moving trailer, the 6.4 still had enough guts to regain speed, just by feeding in some throttle. The temp gauges never budged, with outside temperatures over 82 degrees. The Super Duty has no fewer than five coolers stacked in front of the engine, so we suspect the engine and trans could be worked hard in far hotter conditions without undue concern. The owner's manual recommends going to a 15-40 oil if you'll be towing a lot in very hot conditions. This seems a rational precaution.
It was only when towing down the Cajon Pass that we realized medium to hard braking required a little more effort than what we expected. It wasn't enough to make us uneasy, but it was noticeable, something we might connect with the heavier tongue load. Steering remained within the expectations of a big truck with a straight front axle. It's easy enough to keep truck and trailer within a lane without undue correction, even in the wind. But it's not rack-and-pinion, like an F-150, and you'll know it when you try to drift around a corner.
One of the big selling points of the Super Duty 4x4 has been that the straight axle is easy to lift, making it easier to improve ground clearance by installing oversize tires. Ford's warranty specifically does not cover any damage caused by altering the suspension. Even replacing the wheels with something more stylish, or adding bigger tires with a specialized tread, can compromise the load ratings. When it comes time for new tires, it would be wise to pay attention to replacement tire choices, especially if you plan to tow near the limit.
The transmission is strong, set for smooth shifts rather than direct, hard shifts. It works best when feeding throttle in gradually, where the engine responds"the torque converter stays locked and road speed accumulates gradually. Ask it for instant power, and there's a moment of hesitation before it finds the right gear and hooks up. It's nothing like the quarter-horse F-150 with a quick-shifting six-speed, which is quicker to react and downshifts every time you drop a hint. The Super Duty responds more to a calm, steady hand.
Our sense is that the empty F-250 probably rides a little better than an empty Tundra. Even with nothing in the bed, the ride is far from punishing. You'll know it has two straight axles more by the steering than the ride quality, which is surprisingly good even with 20-inch wheels and rock-hard E-rated tires at 60 psi. We'd expect harsher ride quality as GVWR increases, so our test unit represents the most refined of the breed, but that tells us it's possible to have a decently smooth ride in a Super Duty.
When the F-250 is driven empty, the brakes are remarkably progressive, with an unusual amount of control for a vehicle of this size. Engagement at the top of the pedal is very gradual; there's no squish/grab sequence, just a steady, progressive gain in clamping force and control. Around town, it's possible to make a full stop with no grab or jerk at the end. Still, there could be a little more grip at the end of the braking action, a reminder that long, slow gradual inputs of the brake and throttle are what this truck is about. Our test driver noted the same thing during 60-to-0 panic stops at the track, where it took 161 feet to bring the Super Duty to a full stop. The brakes have great feel and provide a solid sense of control, but when you put your foot all the way into the stop pedal, there's just a little less there.