Well, to be clear, the Wheel is ruled by Jupiter which also rules Sagittarius. Temperance is ruled by Sagittarius. Tarot gets astrologically confusing because certain cards are ruled by planets and other by astrological signs which, being astrological signs, are ruled by planets
What you have to remember is that the planet and the sign it rules are not equal.
Jupiter is expansive and lucky and future oriented. It's about taking leaps of faith, optimism and trust and going for the gold. You can see that if a planet was like that, it'd have a Sagittarius centaur as it's alien creature, racing about, always looking for the next shot to take with its arrow, always aiming to hit the bullseye, etc. (Not unlike the god, Jupiter, throwing his lightning bolts on down at things). This is what rules over the Wheel and Sagittarius. But the Wheel is just Jupiter. Temperance is Sagittarius--which includes all the qualities Sag has thanks to Jupiter.
The reason I brought up Sagittarius to confirm that the Wheel was fire was because every card that is ruled by a planet shares the element of the zodiac signs ruled by that planet. So, HPS ruled by the Moon--Moon rules Cancer, Cancer is water sign, so HPS is water. Mercury is ruler of Magician--Mercury rules Gemini, Gemini is air sign, so Magician is Air.
Does that make sense?