G'day mate and welcome to the forum. As for the Falken Wildpeaks. I can say from personal experience there alright. Off road and on road they work well. Run true and fairly quiet for an aggressive A/T tyre. They balanced up good to. Not many weights. What I do really like about them is the wet weather performance. They are soft and you won't get a huge amount of K's out of them. if you don't do huge K's per year, not an issue but if you do you may want look at other brands. I have never brought tyres for longertivity. I buy them for grip. Mid price point tyres are the go i reckon, you can do better but the laws of diminishing returns comes into play you pay a lot more a little better.
As for the rims. Do you have a Thai of Spanish built D40? The Spanish built trucks have more positive offset. Spanish built you have a few more choices.
Is there any particular reason you want to go steel? There is not much wrong with standard alloys. 265x75x16 is your limit though.