Weight in the bed will make a huge difference, even with crappy tires.
With weight in the back (i.e., everything I own) ?
COMPLETELY different truck! I could go up hills without a hitch, or I mean, without needing to be pulled by one.
The bed was full enough that I didn't need any snow, but I'd have never thought of using something so obvious. Nice.
(In fact, I saw someone driving down the highway here with a bed pretty much full of snow and everyone in the car laughed at it. Never again.)