idiotec

^^^. Just beat me to it. Use a cheater bar.

jk_sea

Tire on the head of a shovel.
Tire on a pry bar.
Tire on a floor jack (if you're in your garage).
Have other people help if they're standing around.
Tire on steel toed boots, ass on the ground, rock your heels back.

Use leverage, save your back!

Chefbrujo

Using body leverage is best and requires nothing.
I just did it with flip flops on this past weekend. 33"s but heavy 33"s.(falken wildpeaks)
So imagine, driver side of jeep. Facing jeep, position mid-rear of the wheel u r putting the tire on. Left knee on the ground, right leg and foot out in front so i can roll the tire onto my foot and use my shin as an assist point and roll tire onto/up shin while leaning back slightly so my right leg/shin is tilting back at the same time im rolling the tire up. Im grabbing the tire with both hands to assist and guide it. I fiddle with it to get the highest lug on and then its easy to center.

If offroad u could always construct a little ramp/rise from dirt, rocks, etc to get it as close to the height u need and roll it on up. If u make the ramp slightly higher u can tilt the wheel in so the highest stud catches the closest hole the kick ramp outof the way and ease wheel onto all the studs.