Hi Jeff, as Frank alluded to, the problem is that 'rubber' parts in model kits aren't rubber,
they are various formulations of vinyl, some of which can remain chemically reactive after
forming. One thing I've noticed is that the softer and more flexible the parts, the more likely
they are to be reactive with polystyrene. The old school vinyl car tires are generally much firmer,
some being downright stiff.