The location of this shelf is in the dead space of the garage on the passenger side of the parking space. Obviously if you were to build this on the driver's side you would not be able to open the door. This is a very important consideration to make whenever building or storing anything on the sides of your garage parking space.
For ease of construction I determined my shelf would use the full 8' length of the 2x4 for both the width and height of the shelf. I determined this by the measurements of my particular totes. I measured the length of the tote and found I could fit four totes end-to-end within the space of 8'. The height of the tote plus 1/2 inch for clearance, plus 3 1/2 inches for the width of the 2x4 and an additional 1/2 inch for the plywood deck would determine the spacing for my shelves. Don't forget to add a small space for clearance at the bottom of the shelf, or you may want your bottom shelf to simply be ground storage. Just make sure to do your math and double check before starting.
You can see the chalk lines on the wall where I marked the studs; mark your studs first, you will use them for a strong shelf.
Each shelf is built with a 2x4 frame with cross members every 24 inches, this will allow a very heavy load on the shelves with no worries of sagging any time in the future. Make sure to use a right angle clamp to firmly hold your pieces on true 90 degree angles before screwing together with two 2 1/2 inch wood screws at each joint.
Use a four foot level when attaching your first shelf as garages have a slight slope to them to aide in water drainage. Pictured below I have my center post attached in a temporary fashion to hold it in place while adjusting the level of the shelf. After the shelf is level both side-to-side and front-to-back, attach it to the wall with a 2 1/2 inch screw through the back support and into each of the studs previously marked.
After the bottom shelf has been decked with plywood, attached with 1 1/2 inch wood screws, it is time to go up. Below I have added the two vertical end supports and next to them and against the wall I have placed temporary blocks to help with the spacing of the next shelf. Simply assemble the shelf, drop it on top of the spacer blocks, check for vertical level on your supports and screw in place with 2 1/2 inch wood screws. Make sure to get two screws into each support and one into each wall stud for the shelf. You won't need to check horizontal level for the shelf because this is maintained from the first shelf with the spacing blocks.
Working my way up to the top, I finished with five shelves, four of which can hold the totes. Fully loaded I can store 16 totes and still have storage for long items like pipe and wood both above and below.
My end tally was two sheets (4' x 8') of 1/2 inch plywood, 17 2x4 studs and a bucket of screws. Entire assembly time was only a few hours including the trips to the home improvement store for the wood.