tyres (and indeed almost all rubbers) have natural oils which keep them supple. the oils will come out over time (that rusty coloured stuff on tyre wall is oils leaching out)
to stop the oils in the rubber been lost you simply obey the law of concentrations. apply a layer of oil to the tyre surface and any oils near the surface will not come out.
it is also a good idea to let almost all the pressure out, this will put the rubber under less strain.
as for the alloys, they should be fine, i've stored alloys for years and they didnt suffer at all.