PR does not expire. Only the re-entry permit does. However, if you leave the country and your re-entry permit expires while you are outside the country, then the government will deem you to have renounced your PR. If you are holding private property I believe you are able to keep it. However, I believe the HDB will reclaim your HDB Flat if you have purchased and either refund you the balance if any after paying off the balance of the mortgage.
I cannot swear by this though as I know in the past one had to give back or resell on the open market but that's been a few years ago.
Two posts and already trying to see how it possible to abuse the system here huh? A dollar to a donut, I'll bet you are from the subcontinent!
One could almost see why MentalDwarf has the attitude he has.
SOME PEOPLE TRY TO TURN BACK THEIR ODOMETERS. NOT ME. I WANT PEOPLE TO KNOW WHY I LOOK THIS WAY. I'VE TRAVELED A LONG WAY, AND SOME OF THE ROADS WEREN'T PAVED. ~ Will Rogers