Yes it could be moisture in the latch preventing it from opening in the cold. Have you checked the tire pressure in your new tires? It could also be that the new tires have more rolling resistance than the old tires. I know that the Continentals are lighter tires. Did the old tires wore out evenly? The dealer might recommend that you do an alignment. If so go for it. If you can do a 4 wheel alignment. I hope this helps.