Go to the Ohio Highway Patrol web site and go check out the state statutes. Should be around ORC 2923.12+. There is no State prohibition against *open* carry, just concealed carry. I have carried openly in Ohio, but there is no preemption law keeping large and liberal cities from passing their own bans, so check your state, county, and municipal law.
Loaded carry in a vehicle is illegal by statute. If you want it as close as possible for self defense use and still comply with state law, it has to be unloaded, in plain sight with action open. Two Ohio court cases say that you can have a loaded magazine on your person and the Ohio Atty General has produced a video instructing agencies that such is the current interpretation, however some departments still don't know about it.
Also, the Feely case (Hamilton County) may expand the rights of citizens a la Vermont...we'll see.
There is a web site that you should check out...I just wish I could remember it.
Do not take my word for it. You must read the law and talk to cops. It would be your chance to educate you, and them.
Rick