Yeap, the 2.125 comp st's where around in the mid 80's, here's an advert from May 85 FREESTYLIN'
I don't ever remember them being around but I remember getting 1.75 front and rear...
with the front end tricks we were pulling back then, a fat tyre on the front would have just slowed you down, but made front hops easier on the wrists maybe!