You sink. I guess it depends on the weight distribution on the toungue when pulling the boat out of the water. If most of the weight is on the back of the boat, your truck will tend to balloon at the rear wheels. Then it's imperative to have 4wd. If you're pulling out a small bass boat, a 2wd should be fine.I have an 04 tundra w 4wd. Am looking at 07 Tundra. I use 4 wd only on wet streets and when pulling a boat up a steep launch ramp. It seems to me that w the anti skid feature I don't need 4wd. But what happens on the boat ramp when there isn't enough traction on back wheels.