Pretty certain if you're lowering the offset, you're moving the rim away from the caliper. This is always somewhat dependant on the design of the spokes etc, however I would make a guesstimate to say the +55's won't clear, and the +48's will (Going on the assumption the stock rims are +53)
On most WRX's the stock offset is pretty close to the calipers
afaik.
Someone correct me if I am wrong here ..