That isnt normal man, unsure of your issue but it definitly shouldnt be vibrating.. I can take tight turns at 40-50 and slide and not get that vibrating.. its only when my wheel is fully turned that it vibrates

 

The tires have about 50% tread left, wear is even. its not bad when i'm on the road, i can't feel a thing. i took an entrance ramp turn at 80mph the other day and it didn't make any vibrations. it seems to only do it mainly during a turn where the wheels are near fully locked. but i've never had a problem like that in previous awd cars. if i'm at a red light, and it turns green, and i make a u turn, if i hit the gas and just go through the turn, it vibrates like crazy. i mean, not like really heavy, but definitely noticable. it kinda feels like my bronco when i had the hubs locked actually. it feels like the wheels are all turning at the same speed. but i dunno.. might be something else.