I tend to be fairly conservative on things like bigger wheels.
I am a fan of doing things right so I'm not "that guy" causing an accident.
To do it right tends to cost a lot more $$$$ than just the wheels. You're probably looking at $2,000 or probably more in "incidentals"
The wheel bearings, steering joints, brakes, and suspension become a real concern when you go larger than 20 or so on the Epsilon Chassis Gen 9 Impala... The suspension is not just the struts and springs. Trailing and lateral arms need to be beefed up among other things. Even upgrading to stockish 18" wheels can be a challenge on the Gen 7 & 8 W-Chassis and that just requires the 18" compatible rear struts and springs along with the SS/LTZ trailing arms.
Wheel bearings, tie-rod-ends, and ball joints are just something you'll get to keep a close watch on and replace more often than you would with smaller lighter wheels and tires.
You can upgrade the brakes to around 13" and maybe larger for $$$$.
The W Chassis A-Arms, and rear lateral & trailing arms can be beefed up with aftermarket tubular parts. The Epsilon chassis can probably be beefed up in a similar manner. Having done just the tubular rear suspension mods I can tell you it's not cheap. If you want to maintain a safe vehicle, once you move to those wheel sizes, it's not an optional modification.
The lower spring perch on the struts may interfere with some tire/wheel choices. If you modify the stock struts you will adversely affect the ride quality and safe handling. Coil-Overs are an option that will not affect the safety and ride quality but again with the BUCKS $$$$.
Not to mention the fact that the rims and tires are ex$pen$ive $$$$.
Standard Comprehensive Insurance will not cover non-stock size wheels if you hammer them on a pothole, curb, or speed bump. You'll have to add a rider to your policy. $$$$$.
Once you do that they know you have larger wheels.
Insurance companies are run by weasels. They are not working for you even though you are paying them. If you have an accident they may force you to prove that the modified wheels and suspension weren't the causal factor before they cover the liability say nothing of the comp and collision claim to your lienholder.