Brood Lord, my new fav unit.

[Norfindel]

What are you talking about? Marine/Medic + Tanks was a very common build in professional SC1 games against zerg. It has only recently become less popular now that terran sometimes uses a mech build against zerg. But otherwise, it was pretty standard to get tanks to support your marine/medic balls.

Sorry, too used to Pv? games
Still, if Zerg units get too close to your Infantry you will get splashed by your own Tanks. Granted, if you have enough units, it's unlikely that a Zerg unit will get too close, unless it's an Ultralisk.