1990 WTA Tour
The 1990 WTA Tour calendar comprised the four Grand Slam tournaments , the WTA Tour Championships and the WTA Tier I , Tier II , Tier III , Tier IV and Tier V events . 
<triplet> 1990 WTA Tour <subj> 1990 <obj> point in time <triplet> WTA Tier I <subj> 1990 <obj> inception