I have an old set of Sears Jack stands that are rated at 6 tons per pair. My old 3 ton floor jack is marginal in lifting the front end of my F250 gas truck - it will do it, but barely. I just rotated my tires a few days ago, and I did the front one side at a time.
I second the opinion of avoiding the HF cheap stands... They had a recall not long ago on some jack stands. I will say their terms for replacing or refunding were very liberal.
Harder to find, but if you're supporting an F250 you may want to look for some taller jacks rather than the typical automotive stands. I use 4" of oak under mine for the extra height (and to keep them from gouging the pavement).