Tire size, what would look best?

[myyamr7]

I just bought some Chrome Smoothies for my truck, 15x8 and need to buy some tires now. I haven't bought vehicle tires in years, so I'm kinda clueless and would like some knowledge before walking into the tire shop.
My truck now has 225/75/15 on the original wheels. Measuring the height, seems around 28". I'd like to go a little bigger to fill wheel well a little more, so I was thinking around 30"
What number should I be looking for in a tire that is close to 30" and fits properly on the 8" wheel? Seems with a 15" wheel, the sizes are limited around 30"

Not my truck, but this is the look I'm going for. Thanks in advance