Well, im about to take a long road trip in the 89 IROC. I have a set of 15x4 wheels up front with Kumho 165 80 15 tires. Can somebody with knowledge in this topic please tell me if this is a good or bad idea. Also, what psi should I run in these tires?

When I was into VW Bugs, I used to run temporary tires normally. CHEAP to replace (sometimes free) & lasted pretty good.

Sucked to make a quick turn at speed though. Crank the wheel & the car kept going straight. So straight I had time to past my turn, straighten the wheels out & keep going. Never swerved any!

The weight of a V8 over the fronts would be a little different though. But still, narrow street tires would be fine, just still the same basic thing. Not much traction for turning a speed.

load rating should be no less then 1000lbs ea

you can run 45 PSI.or more
and drive like the cops are watching you..and you should be good.
this way you can make all your turn offs..LOL

i run 165/80r15's up front with 50psi
load rating is like 1240 ea..
and have been driving with this size up front on the Hot rod (92z28) for
the last 17 years..

To add to what Stephen said... Also be aware that it's gonna affect your braking distance. Should be safe on the street, lots of guys run them. Just give yourself extra distance between you and the car in front of you

ya thats the other thing..give your self more room to stop..
in city is not bad at all.. it's about the same..

Put your stockers back on!!!! To many distracted A-Holes on the road willing to throw you out of your lane... On a long road trip your car should be at the peak of its capabilities... So needless to say, this is not the time to sacrifice braking and steering quality... You never know what's coming around that next bend...