questions:'86 4kQ tires + tire pressures

[sabuti@nyc.pipeline.com (Sabutin)]

--Further on...third week adventures w/my newly acquired '86 4kQ. 
1-The car came w/new tires...Ultra Tech GT+4. Never heard of them. No other
name on the tire. Anyone know who makes them, anything about them? I
haven't pushed the car much yet, a couple of exit ramps is all, so far the
tires haven't complained and feel OK. 
2-I've been experimenting w/tire pressures...at the recommended light load
28psi the car feels numb,turn in's not crisp; at the high load
recommendation, 34psi, w/ only one passenger, the car feels more alive, but
has SERIOUS bump understeer problems. Brought the fronts down to 31psi,
feels better. However, I've read several posts that recommended higher
pressures in the front. Is this a front end/suspension problem? Anybody
have any recommendations? 
Thanks, 
Sabutin