If you're sticking with 33's, personally I would stick with the 285's rather than step up to the 315's (12.5in) as now you need new rims and new or additional flares to cover them. Strictly speaking they are also not legal on a JK as the rim offset will be much more than an inch each side if that bothers you.
The wider tyre will also cause more drag/friction on the highway and will drop fuel economy - also only a problem if that sort of thing worries you