Deck stairs
 

Three-tread stringers coming down to asphalt driveway which slopes from right to left as well as being bumpy. I can make each stringer a different height ,at the bottom,but what happens when the asphalt changes its shape,again,in the future ? I thought about putting down a piece of PT planking for the stringers to rest on. That way they would all be the same size and shape and they could be shimmed,if necessary,at a later date. Anybody have any suggestions ?

Concrete Slab
 

Form and pour a level concrete pad upon which the stringers can land so they can all be equal lengths. Building codes require it.

This pad should have an area at least 3'x3' upon which to step at the bottom.