I have found this on Reddit.
Tip 1: First of all, damage to vehicles (planes and ground alike) is localized which means that shooting one part of the tank will hurt that part. You may have noticed it says that you've damaged a track or more, which means that you can focus your damage to incapacitate or destroy the vehicles.
So when you are going head to head with a tank using AT grenades, hitting the actual tracks will disable it on the spot which is great if you want a quick getaway. However hitting the cannon will disable it stopping the driver/gunner from shooting you. Combine both these and you can take one out easily with a little teamwork.
Tip 2: If you are a scout and you're against the light armoured truck, your K Bullets will not only damage it but also penetrate and damage the occupants if you shoot the right place (Noticed this one earlier when I killed the gunner of one).
Tip 3: As long as you're near the main village you have the advantage; tank drivers and the gunners do not have the ability to aim high enough to kill players constantly switching buildings and running to roofs. High roofs mean easy target for AT grenades.
Tip 4: Cavalry have amazing AT potential so long as you dug and weave while your AT grenades recharge. And you provide a great distraction whilst others come to help you.
I want to add that, if Battlefield 1 is based on true data about World War 1, every tank has one true weakness: it's their back.
Since the first tank created to our tank now, they where created so that their front part where "theoretically" indestructible so with all the "iron/steel plate" in front the back where not protected, so the tactics were to get around the enemies and destroy their back.
Also the tank tracks are weak, so if you aim for them and destroy them the tank cannot move anymore and so are strongly in danger. I hope I have responded correctly and enjoy the game.