Newb Finally starting my project - help picking wheels

[rchadhaney]

I'm a newb to actually posting on this site but I've been here over the years several times for information.

When I was 15 (12 years ago) my grandma gave me my grandpa's 1980 chevrolet Silverado 2wd 1/2 longbed. Over the years I've done work a little work on it but it hasn't been on the road since 2006. I am finally starting to work on the truck again and one of the first things I'm wanting to do is get new wheels/tires. The truck currently has 15x8 rallies with 255/70/15r's. I want the wheel well to be filled out and I want a little bigger wheel. I don't want an uncomfortable ride. I'm thinking 17's but I'm wondering if those will be big enough to be noticable but small enough I can get a decent tire on it? Should I go with 18's?

Here's what I've been looking at..