Simple project, but I need some advise please.

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Guys, I am a newbie at working with metal and have a little project that I need advice on.  This is a real simple project with no welding involved, but I will be working with angle iron.So here goes.  I want to build a wheel rack that I will attach to the 6"x6" posts in my shop which are ~8' on center.  This rack is actually a single shelf type of rack.  My plan is to use a piece of angle iron that is bolted directly to the posts with the angle pointing out.  I will then use an identical piece of angle iron that will be attached to the first piece by bolting 4(?) pieces of ~10" angle iron to the bottom of both long pieces.  To support the front piece of iron I plan on using chain that will be bolted to the front piece of angle iron on one end & then bolted to the posts on the other end.  Did I explain this well enough?  The wall mounted rack/shelf will basically be a triangle with wood, the posts, being on the vertical side.  Angle iron will be the horizontal side & chain being the angle side.Now I have two questions.  1) What size of angle iron should I purchase?  I am estimating that the total weight of the wheels, no tires, could be in the 300 to 350 pound range so would angle iron in the 2"x2"x1/4" size hold that weight?  I talked to a steel supply house & they would not give me any type of rating for the steel - CYA I would guess.  Is there some type of rating system for angle iron?Question 2)  I only have basic drill bit set so I know that I will have to purchase a bit or two to drill the holes that my project requires.  What bits should I purchase?  I do have a drill press btw.So if you have any suggestions, ideas or questions I would sure appreciate hearing from you.  If this rack works out, I will probably build a couple more.  Kinda like condos, ya know?   Thanks, Scott
Reply:Should work OK.  You can use a lot lighter angle if you put one or two cross pieces at 1/2 or 1/3 of that 8' span.  I'd say 1/8" angle would work out OK if you did that. These would be in pure tension (unlessl you set a tire on them)  so they could just be flat strap.If I understand correctly, the tires will be supported between two rails. The rear rail (near the wall) needs enough spacing from the wall so the tires clear the wall (might be easier if this is an unfinished wall)Put the top of the chains as high as possible.  The tension in the chains (and strain on the anchors and posts) gets multiplied by the secant (1/cos)  of the angle from plumb. If the chains are vertical, this factor is one, if they are horizontal, the factor is infinity.  Similarly, the wider the shelf is, the more the tires will tend to spread the two sides, so keep it as narrow as practical...which will also help keep the chains vertical, and make it easier to stow or remove tires....and this will make the tires less likely to turn and slip between the rails.Pay attention to the anchors for the chains.  lag type screw eyes will tend to split the posts. It is better if you can make some plates that spread the load out to several fasteners, or if you drill through the post and use a nut and big washer on the back.  You might want to include some turnbuckles to level the shelf.
Reply:Thanks, kevbo.  Appreciate the feedback.Btw, these shelves will be holding only unmounted wheels with no tires, so spacing against the wall will not be an issue.Interesting what you said about keeping the chains as vertical as possible to lessen the tension on them.  I think that the shelves will probably be in the 10" wide range so I will try to maximize the height above the shelf that I attach the chains to the posts.  I will need to make sure that I don't attach the chains to near to the top of the posts because I would imagine that I might run into a problem of splitting the posts at their top & have the whole thing come crashing down.  Not good since the shelf will be ~9' above the floor & I can just see the wheels bouncing around off everything below them.   Also, as I have thought more about this little project, I don't see any reason why I shouldn't go 16' instead of 8'.  I have plenty of wheels that I need to get off the floor and it won't much harder to double the length of the shelf.Also, another good idea about using some sort of plate to spread the load at the post mounting points.  I can see how it will help at the location where I mount the back piece of angle iron directly to the 6"x6" posts.  I'll give it more thought.  I had already planned on drilling the hole through the post where I attach the chain and using regular bolts instead large lag screws.  Glad to see your suggestion reaffirmed my thought.  Turnbuckles?  Turnbuckles?  If I measure everything correctly I won't need no stinkin' turnbuckles.      And while I definitely don't want to under build the shelf,  I may drop down to 3/16" angle iron instead of 1/4" in order to save a buck or two.  But 1/8" kind of spooks me, only because it sounds too thin & I am very unfamiliar with the load capacity of steel.  I do plan on installing cross braces and will be using angle iron for them also.So, it sounds like I am good to go unless someone else cares to chime in.Thanks again, kevbo.  Scott