My wife and I are having a disagreement about four wheel drive. We own a motor home with dual rear wheels, and my argument is the fact that it has four wheels driving it just like a four-wheel drive truck. I'm sure that it couldn't keep up with a 4x4 climbing mountains, but it should have equal traction on level ground. Please tell me I'm right or I may never live it down.
Dual rear wheels do help with traction and payload capacity due to the fact that there is twice the amount of rubber touching the pavement at the drive axle. But you don't have a case when comparing this to a true 4X4.
First of all, there is a tremendous traction advantage by driving the front wheels with the weight of the engine holding them down. That's the main reason a rear wheel drive car is no comparison to front wheel drive traction in foul weather road conditions.
The next 4X4 benefit is simply having the drive wheels at all four corners of the vehicle. The various different transfer case and locking differential set-ups allow several combinations of torque application to the wheels. The ultimate traction is obtained by locking the front and rear axles together along with the use of locking differentials which enables all four wheels to turn in unison over harsh terrain.
Good luck with that.