Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: What are the wheel dimensions? 4 inches perhaps?
Document: It is very rugged after assembly.I have the same larger (4 ft wide by 6 ft high)  version of this shelf in my garage. some shelves have over 250 lbs on them.
The cart rolls around very easily and parks extremely well because of the 4 swiveling caster wheels. The shelves are rugged and have sides to keep stuff from falling off when moving the cart . Count your &#34; notches&#34; from the bottom before putting on the upper two shelves.
I guess those who build them know how they work, and cannot foresee questions that some of us will have.As one example, there are little white washer-like bushings in the package. What are they for? Apparently, they go between the wheel assembly and the post. They don't appear in the instructions at all.Also, the black plastic bushings that you mount the shelves on have an orientation that has to be right.
Size is misleading shelves are actually 14&#34; x 24&#34; with a 4&#34; handle added making it a total of 28&#34;.Size shown on the box show as 16&#34; deep the only way to get that number would be to measureat casters with both pointing out.Color is also listed as black but is a gray and black hammer tone.
I bought this to keep my Cricut machine and supplies organized. It works great as I can easily wheel it in and out of the closet and keep items out of sight when not in use. Assembly was easy and the cart is durable. I wish it came with one more shelf as there is a lot of space between shelves. Good if you are storing larger items.
well built, easy to assemble, helps us keep our work area organized., and demands for eight more words sucks. Who made that ignoramus rule?
well built and good price...vendor very responsive....roomy and well designed, open grills preferable to solid shelves...rolls smoothly...frees up much needed counter space...recommended
this is a very nice cart. it is very sturdy and is a very nice size. It should last for as long as you want it.
this cart was very easy to put together, very sturdy and easy to move. exactly as shown. Using to store heavy containers of soap making oils.
printer cart and hanging backpacks and computer bags from in a small space. nice for the purpose. Have several other alera racks and love them.
Answer: The casters are 3". All swivel and two of them lock. Hope this helps!