rear tire leaks, bad rims? Options

[Crzybakerdog]

so i got new winter tires about two years back and threw a pair of those on the rear and moved the old rear ones which had nice tread still on them to the front. since this year recently the rear tires lose pressure in about a week or so. is it possible that the rims are bent and that air is leaking where the tire meets the rim. the tires arnt that old and i dont drive crazy but they lose air all the time and i need them to stop so i dont have to fill them up in the winter. Any thoughts on why they lose air pressure so fast?

[celicaST]

since you say both rear tires are losing pressure quickly, id be surprised if it was due to a defect in the wheel/tire. make sure you are are inflating cold tires (wait after driving). inflating into a hot tire will cause your tire pressure to be lower when their cold. other than that cant think of anything else unless you have a little brother thats deflating your tires