Why did the Tiger tank's gun and armour reduce its mobility and reliability?

The Tiger tank (Pz. VI) prioritized firepower and survivability to an extreme degree, which directly impacted its performance and mechanical stability. Its massive 88-mm high-velocity gun and heavy armour—ranging from 100 mm at the front to 80 mm on the sides—resulted in significant weight, with early models reaching 55 tons and the Tiger II reaching 70 tons.1

This substantial weight severely compromised the tank's mobility, limiting its cross-country speed to approximately 20 km (12 miles) per hour. Furthermore, the heavy design placed immense strain on the vehicle's mechanical systems, making the Tiger prone to frequent breakdowns and difficult to maintain in the field. Its operational range was also restricted, requiring refueling after only 70 to 110 km (45 to 70 miles) of travel. Consequently, the Tiger was most effective in defensive roles where its lack of speed and agility were less critical than its ability to withstand and return fire at long range.1