PSA: Tanks may have weaker defensive stats in lane after new runes
But their damage is gonna be much higher. Lemme explain: almost every champ in the game lost 12 early mr from the rune rework. Mid, this might not have much of an effect, as most AP mids ran pen marks (and maybe quints) and a fair number ran AP glyphs, and therefore didn't have the me in the first place anyway.
Top lane, however, is completely different. Most top lane tanks didn't run pen, due to the need for attack speed or ad to last hit under tower - INB4 "I ran 30 mpen top see worth no other runes" that's fine, that wasn't standard practice. No Jaycee or Riven worth their salt is gonna splash into the defensive tree for 4 early mr (yet), so your magic damage abilities will be hitting much, much harder, in most cases.
I know you may feel a lot squishier, but trust me: champs like maokai, Malphite, and even Sion (e max anyone?) are gonna be doing a lot more damage, even if they spec full defense. Keep that in mind as you experiment with the runes.