FR185 is a recording speed on the manual setting on JVC DVD Recorders. It's the one I (and LS, Mark, others) use the most. With this speed you can get about 4 hours of video on a DVD, once commercials are used. It's great for cartoons and some live TV shows. Depending on what you record, you may want to use a slower 165/155 speed or one of the presets. Just start with that and experiment.
When I say I can fit 4 hours, I'm talking about after I remove commercials. I record shows from my Tivo to the JVC on DVD-RW. Then import the files on the computer and remove commercials and author menus.
So, FR 185 on JVC will get approx. 3 hours per DVD.