If you go with 295/40's you will be almost 3/4" larger diameter than stock, which doesn't seem like much , but you could get into a tire rubbing the inner fender situation.
Stock diameter: (18's) = 32.6 Inches
305/35 24 = 32.4"
295/40 24 = 33.3"
There is a great website that calcs this for you but it only goes up to 23"
Just remember that 22-24" wheel/tires usually add about 30lbs of unsprung weight to each corner of the Armada. That is the same as 240lbs of static weight per corner.
So when you hit bumps and potholes, your wheels are going to bounce bigtime. That's what most people are feeling. Then the low profile tires with less rubber on side walls will even make it worse.
I put 24" on mine and yeah it is a little bit more ruff but it just means that you need to take a little extra care in avoiding pot holes. I love how it rides on the freeway it is just as smooth as the stock tires. I guess you have to sacrifice ride for looks. It is all into what your into. Just to answer your question I have 305/35/24 KUMHO ECSTA and they dont rub at all. I hope this helps you decision!
Are any of you guys with the big rims bending them????
I went through the low aspect ratio tire thing a few years back with two different european sports sedans. Not only did going down below 55 aspect ratio dramatically increase the stiffness of the ride, it put the rims so close to the ground that I bent rims, front and rear, more than once on both cars from hitting potholes. It got old after a while and expensive.
I can turn the wheel lock to lock with no rubbing with out the front mudflaps. I just installed the front and rear mudflaps and the front ones rub on full lock turn. I cut the inner part of the mudflap 3 " and now, no rubbing. The front mudflaps are not flat, they have a curve towards the inside. If you are not using the front mudflaps, no problems.