I would increase the movement of all tanks by 1, and make them wheeled or something. (if you haven't already) The average foot speed of infantry is about 3 to 4 mph (4.8 to 6.4 kph).
Personally I would increase the Panther to 13/6, and the Tiger II to at least 15/8.
Panzer IV would depend on which model you intend on using...I would assume you'd probably want about a 1942ish one, which would be the IVG or H. I'd probably say 11/5.
I would also add the KV-2 for the Soviets, with 14/7 stats, and 3 move.
I'll post later an additional tank for the British and Americans, so each nation has two.
As for the Anti-Tank, no one said that the Civ III developers were perfect with regard to historical accuracy.

Take my word for it, they were used mostly on defense, shooting at tanks as they approached. Though later in the war, the Germans and Russians in particular had self-propelled anti-tank guns, which eventually were superior to tanks in firepower and defense. (Juggernaught and Su-152 come to mind respectively)