First of all, welcome to J-O!
I can't believe nobody has answered your question yet, that's pretty unusual for this place.
We may need a bit more info before we can safely answer your question. What kind of tire are you running, all-terrain, mud terrain, or street tire? How much tread is left on the tire? I'm guessing there isn't much, regardless of the type of tire, as a good tire with good tread shouldn't hydroplane at 35mph. But, since you're thinking of replacing them, this isn't an issue right now. As for what type of tire to get, that's a little different. I can pretty much guarantee that a good mud terrain tire won't hydroplane (unless you're doing 70 mph through 4 inches of water on the road). However, if you never plan on wheeling the Jeep, a mud tire is a bit of a waste. You could conceivably get away with running an all-terrain tire. For fuel economy and less wear and tear on the drive train, go with something in the 30" x 9" size.
Also, since you're dropping tire size and are concerned about rollover potential, I'd suggest getting rid of the body lift and going back to stock bushings. Generally, anything over a 1" body lift is not recommended, as it puts more stress on the body mounts and can create too much body roll in cornering and off-camber situations. If you have any mechanical aptitude and a place to work, you can replace the body mounts in a few hours.
I hope this has helped you out. If you have more questions, feel free to ask and hopefully someone will answer faster the next time. Until then, enjoy your Jeep!