[dubs68SWB]

9 years of tire experience.....If they are modern radials, it doesn't matter a bit. Unless you are mounting them yourself and trying to air them up with a $19.99 roadside inflator that plugs into your lighter, the tire shop will have no problems airing them up. Whether you stack them up or on their sides, it just isn't going to matter! The weight of a vehicle can have an effect over time, but once they get warm from driving, they will be round again. The main thing is always the elements. Keep them out of the weather and the sunshine. Simple!!!!