An amphibious tank is similar to an ordinary one only at the first glance. It has a large-volume body, a thinner amour, and water-jet propellers. In the first instance, designers are striving to reduce the weight of the tank and optimize all of its units. On the other hand, the shape and volume of the tank body must ensure sufficient floatability. In this context, it is noteworthy that used are any resources that increase the tank floatability.

The Memorial of the Korean War in Seoul has two armored cars standing stern to stern – the Soviet tank T-34 and the Chinese amphibious tank “Type 63”.
Of particular interest is different construction of track rollers of these tanks. The track rollers of overland tanks have a thick cast rim, whereas those of amphibious tanks are made in the form of a hollow barrel. Such track rollers are undoubtedly lighter and the air cavity inside the track rollers provides a considerable buoyancy force, although not too big. 

Here we see a typical example of proper use of resources.