The T-55 is most effective against light to medium armor vehicles. The basic ammunition load for the main gun is 43 rounds. External fuel cells make the tank very vulnerable, as does its thin armor protection. The T-55 has a limited ability to depress the main gun, hindering the tank’s fires in defilade from high ground. In addition the gunner’s primary sight is slaved to the main gun, which does not allow the gunner to acquire targets in a hull-down posture.
Although the half-egg shaped turret of the T-55 has good ballistic qualities, it provides cramped working conditions for the crew, resulting in a slow rate of fire; and the protection afforded by its low silhouette (1 meter lower than the M60) is counterbalanced by its poor armor protection which is thin by western standards. By the same standards, its gun control equipment is also crude. It shares the disadvantage of most Soviet tanks in having limited ability to depress the main gun, thus not being capable of firing effectively from defilade and being forced to expose itself to engage targets. Ammunition and fuel are stored in vulnerable positions. The lack of a turret basket presents loading difficulties, and there is limited ready ammunition. The driver, commander, and gunner are all in line.
The T-55 is not airtight. Although crew members are protected from radioactive dust by the filtration system, they must wear individual protective masks and clothing to guard against chemical and biological agents. The tank must thus pass through contaminated areas rapidly and then be decontaminated before it is fully operational.
The tank can be made watertight for fording water obstacles up to 1.4 meters deep (5.5 meters with snorkel). However, it may take up to half an hour to prepare a medium tank unit for a snorkeling operation, and entrance and exit points may also require preparation.
