Tires: Cupping tires - shocks?, bias ply tires, inflation pressure

Question
I took my Trailblazer to Tires Plus this weekend for an oil change and tire rotation.  The tech advised my tires were cupping due to the shocks that needed to be replaced every 55K miles and I'm just over 65K.  Only the front tires are cupping.  He then proceeded to price new tires for me and not new shocks.  My question is does the need for new shocks make the tires cup?

Answer
Regina,

The term "cupping" is applied to quite a few different things.

Technically it ought to be applied to situations where the shocks are bad or there is a balance problem.  It was easy to diagnose this when there were only bias ply tires, but modern radial tires make it difficult to  distinguish "cupping" from "irregular wear" - which is caused by misalignment and aggravated by insufficient tire rotation and insufficient inflation pressure.

So I would first get an alignment and see where that leads.