Elves were genuinely stronger than Dwarves and Men
A reference which supports the view that Elves were stronger than Men can be found in JRRT's Commentary on the Athrabeth in HoME X (Tolkien is comparing men and Elves here):
"They (Elves) were thus capable of far greater and longer physical exertions (in pursuit of some dominant purpose of their minds) without weariness; they were not subject to diseases; they healed rapidly and completely after injuries that would have proved fatal to Men; and they could endure great physical pain for long periods. Their bodies could not, however, survive vital injuries, or violent assaults upon their structure; nor replace missing members (such as a hand hewn off)."
"He was as tall as a young tree, lithe, immensely strong, able swiftly to draw a great war-bow and shoot down a Nazgul, endowed with the tremendous vitality of Elvish bodies, so hard and resistant to hurt that he went only in light shoes over rocks or through snow, the most tireless of all the Fellowship."
- JRR Tolkien, Book of Lost Tales 2
"Legolas watched them for a while with a smile upon his lips, and then he turned to the others. 'The strongest must seek a way, say you? But I say: let a ploughman plough, but choose an otter for swimming, and for running light over grass and leaf, or over snow--an Elf.'"
-JRR Tolkien, Fellowship of the Ring
"In those days Elves and Men were of like stature and strength of body, but the Elves had greater wisdom, and skill, and beauty; and those who had dwelt in Valinor and looked upon the Powers as much surpassed the Dark Elves in these things as they in turn surpassed the people of mortal race.
Immortal were the Elves, and their wisdom waxed from age to age, and no sickness nor pestilence brought death to them. Their bodies indeed were of the stuff of Earth, and could be destroyed; and in those days they were more like to the bodies of Men, since they had not so long been inhabited by the fire of their spirit, which consumes them from within in the course of time. But Men were more frail, more easily slain by weapons or mischance, and less easily healed; subject to sickness and many ills; and they grew old and died."
- Of Men, The Silmarillion
As far as maximal strength, an active Elf is more likely to build it quicker and can potentially achieve a higher lifting max above human plateau. Though Elves didn't tend to work maximal strength, more endurance strength. The Great Orcs like Bolg did achieve that level of maximal strength.
Elves are the Vulcans of LoTR.
I'd reckon ancient Elves like Galadriel possessed downright super human strength. A Maia like Sauron, even before his armored form, or Manwe would be a lot stronger than that.
Tulkas is Hercules.