If your alloys are like mine they corrode a bit and are quite hard to remove, the natural instinct is to get a lump hammer and start pounding - STOP - you will mash up your alloy (don't ask me how I know that)
Let me show you a better way.
Step 1: Jack and Chock
Hopefully I dont need to tell you the importance of this step.
Also you probably want to do it a bit more properly than me, but anway just make sure you do it.
park on flat ground (I forgot that one once and had a bit of a hairy moment as I rolled along with my Landrover on top of me) Jack, add secondary support and chock some wheels
Step 2: You Will Need
A stout peice of timber and a ratchet luggage strap
Step 3: And Do It
Feed the luggage strap through the slots in the rim (make sure it dosn't go round the brakes or anthing else behind the wheel) and clamp the timber to the wheel as shown.
To avoid scratching the rim then make sure no metal parts of the strap touch the rim.You might also like to put some rags behind the timber just for extra protection.
Ideally the timber will rest on both sides of the tyre.
Now (assuming you have removed the wheel nuts!) gently work the wheel back and forth slightly using the long lever afforded by the timber.
If all goes well you won't need to apply much force or move the timber back and forth too far.