If you've ever had a bike tyre that you can't get onto a rim, you've likely known the horrible pain of blistered palms. Over at Global Cycling Network, they show of a few tips for forcing a stubborn tyre onto the rim without destroying your hands.
The first tip they show off is to make sure the tyre's bead is resting in the centre of the rim. This helps because the centre is lower than the edges. From there, they also suggest warming up the tyre or pushing the section over the valve last. For those truly stubborn, awful tyres that have you screaming at your wheelset, they suggest lubing the bead of the tyre with some soap and water. Just get some soapy water, rub it around the stubborn section of the bead and it will almost always slide right on.