I have a car with full coverage. When I read the document explaining my insurace I see no mention of rental car coverage. I hear folks say all the time that they use their insurance for their car on there rental.

Is it rental coverage is so obvious that they dont need to mention it? Or is my insurance lacking rental car coverage?

Every company is different, the best to do is to take contactwith your agent (company) and ask him to specify and clear up this matter with you! Don´t believe other people, they will not pay you in case you need it!
Greatings
G.

i called my agent i have Allstate insurance she said any were in the u.s so out of us you might wanna think about getting it

Not all insurance will cover while you are traveling, check with yours. Most US insurance does but you always have to verify what kind of coverage they will offer. Some are only liability, what about collision? If you are not sure, contact your insurance agency or pay the rental company, be always at the safe side.