Just a word of warning, I had my hard doors hanging on similar hooks and the
> two inch screws provided pulled out of the studs. The doors crashed to the
> floor, bending and scratching them. :-( I remounted the hooks with 4 inch
> lag bolts and havn't had a problem since.
>
> Here's a link to my hardtop hoist plans
>
>
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Yep. When you use any hook on a garage wall, throw away the screws they come with and use at least 3" bolts. It's a good idea to drill the joists first that way you don't split the 2x4 with a bolt. Just make the hole slightly smaller than the solid center on your bolt.
Never trust anything anchored to just sheet rock unless you use a molley-bolt or toggle bolt. Those plastic push-anchors and not good for heavy loads.