You are running tires that are 30mm right now and have 8mm of space between the tire and contact points, and you think a 45mm tire will fit comfortably?
I would check that math, or maybe you and I have different definitions of 'confortably'.

If you run 32mm tires that measure 30mm right now, they are good in unpaclved sections, and you ride mostly paved roads, I wouldn't go a lot wider, simply because there isn't much to gain.
Maybe a 38mm tire since it would likely measure closer to 35mm on your rims.