We're both kind of right. This is what I found from the Ohio Highway Patrol website. As long as you have mirrors any rear tint is legal
http://www.statepatrol.ohio.gov/FAQsequipment.htm
What percent can windows be tinted on the vehicle?
According to Ohio Administrative Code 4501-41-03, on Ohio registered vehicles window tint must allow 50 percent light transmittance on the rear and side windows, and 70 percent transmittance on the windshield. In other words, the tint can not be darker than 50 percent on the side and back, and 30 percent on the windshield.
Light transmittance of 50 percent does not apply on the windows behind the driver if there are outside left and right side mirrors. Remember, auto glass is slightly tinted from the factory and will make the tint you apply to your windows darker than advertised by the tint manufacturer.