New rims, Need some tire size help.

Use same size front and rear then you can rotate them. Tire manufacturer and size are like mufflers, To each their own. High mileage tires suk in the rain as do Drag radials. First look up what the tire numbers mean and get some that fit You.

First of all how wide are the wheels you're buying?
IMO they'd have to be at least 9.5" wide to justify a 305 width tire.

And I would get at least a 45 series sidewall on 18" wheels to fill in the fenders, and to not stray far from the stock tire diameter.

Setup sounds fine to me. That's just a little wider, but similar height to what I'm running with
255/45-18 Front
295/45-18 Rear

If you get a lot of rain, and plan on driving in it (or know you'll get caught in it a lot), I'd stay away from DR's on a daily driver. They are quite dangerous in the rain. If you DO get stuck in the rain, turn your traction control off. If you do hydroplane, traction control tries to modulate the throttle and the car doesn't react the way you think it would, so instead of being able to correct it, you end up going sideways.

If you will only be driving it in good weather, then go for it.