[racer_d]

While it might cause surface corrosion to the shocks, it also reduces the pressures on the suspension bushings. This can cause problem when the car is lowered again and asked to support weight that it hasn't for months. Not sure what year the box is, but you could put the spare on in place of the flat while you have the flat repaired.

In the end, its your car, and your decision. I like to think the manufacturer knows what is good/safe for their product.