What would be a good humidity range to keep your guns with wood stocks, so that nothing happens to them?

Keep them in the humidity of your area or they might chsnge point of impact when you take them hunting (in that area).

Right now I am keeping my guns in my furnished basement, I have noticed some cracks in a couple rifles around the grip that were not there. I have moved them upstairs and am not monitoring the humidity of each area. I am wondering what is a good relative humidity percent that is safe for the guns. Any help would be great, or if anyone knows where I can find out. Thanks again.