A 16% grade is a long way from a 25% grade and then add it being a dirt road on top of it. Not buying it! A graveled road at least has stones to anchor the dirt somewhat and provide some added tire grip but still washes away quickly in rains. The slightest rain or water flowing down a 25% grade would wash the dirt away in minutes. Tires would skid down a 25% dirt grade with the approx 3000 lb weight of a TC on the back pushing it. Brakes would be useless as all they would do is prevent the skidding wheels from turning.
We've off-roaded in the steep glacial moraines and ravines dirt jeep trails in the 532,000 acre Manistee National forest where we've own acreage for over 30 years and know what a 25% grade is like even with a 4 wheel drive unloaded deep lug tires on jeeps and Geo Trackers. No way could a pickup with a heavy TC on it go up a 25% grade of dirt or even attempt going down for over a quarter mile distance of straight road as the vehicle would become totally uncontrollable with the locked up not rotating front tires. Unsteerable! Come here and I will show you and watch you gasp! They are usually our snowmobile hill climbs and motorcycle dirt bike hill climbs. About 20 miles away is Sliver Lakes dunes and the dune buggies and they know what it takes and what it's like to go up and down steep dirt and/or sand hils. Very special built and a light as possible with a big and wide a lugged tire as possible aired down to 15-25 PSI.
Ever see what even slow flowing water does to even well graveled roads with a 3% grade? Road crews struggle to barely keep them usable!