Tank stats explanation

1LT_Dwayne: I was playing the AMX 40 and I could barely reach 25km/h on hard ground even with a turbo. That stats is pretty weird because what's the point of giving a tank a good speed value if you give it terrible ground resistance? From my perspective the max speed should be the speed on hard ground and then you add the resistance value on med and soft ground. Is there something I don't understand here?