Thicker wood will be able to support more weight. If you have an unfinished garage, you can use the 2-by-4s in the wall frames as the columns, almost like you'd use 2-by-4s for building DIY shelves.
Learn more about your options for this job. You can build a storage loft in the garage that's supported by posts on the ground. Thicker wood will be able to support more weight. If you have an ...