The 4 wheeled unit is designed for larger pools. There is also a convertible versions that can work off either suction or pressure.

Scott

My pool is approximately 35 x 17, and we had the 2 wheel model, which worked pretty well, but seemed to spend more time in the deep end, rather than the shallow end. I believe the 4 wheel model runs straight for longer length, and larger pools as you said. Do you think I would see any difference by using the 4 wheel model, even if my pool is not considered a "larger" pool, or should I save my money and stay with the 2 wheel model?

Our pool is 22 x 19 and I need to get a cleaner and was looking at both of these models. Curious what everyone thinks.

I have the 2 wheel model on a 36x18 pool. I can get away with the smaller unit because the suction port is midway between the long ends. The cleaner does seem to stay in the deep end more but I think that has more to do with the floor slope and gravity rather than 2 vs 4 wheel model. I have read that those with the 4 wheel model have a similar issue.

great responses by everyone, thanks. My father in law has a dog he adopted from the pound, and it goes in circles, one direction only, kind of like my pool cleaner right now. It has cleaned my deep end nicely, but isn't going up the slope to the shallow end. It used to work properly....but who knows. Anyhow, thanks.