How fast do four Tire-Propellers have to rotate to lift 2000 lbs?
Let's do a back-of-the-envelope estimate. As a simplifying assumption, assume that a propeller generates lift by accelerating air through an opening of a particular size, at one particular speed. The formula for the amount of lift generated in this case is:

$$\text{Lift} = \text{Opening area} \cdot \text{Air density} \cdot \text{Exhaust speed}^2$$

For each propeller, the needed lift is 500 pounds force, and the area of each opening is $\pi \cdot (\text{$9$ inches})^2$.

So we can calculate the needed exhaust speed using Wolfram Alpha: square root of (500 pounds force / (density of air * pi * (9 inches)^2))

The answer comes out to 230 mph. That's the speed that the air has to move downward through the rotors. I don't know how fast the propeller will have to move in order to make this happen, but it will be a comparable speed.

The amount of power required can be found by multiplying this number again by the amount of lift. According to Wolfram Alpha, that comes out to 307 horsepower (229 kilowatts) per rotor. So about 1,200 horsepower for the entire aircraft, if the rotors were 100% efficient.

Good luck with that.