SixteenStepStairs

MESH STAIRS

1 prim

You can resize the stairs in any direction.

I enlarged the stairs to 10x10x 4 and they were still 1 prim. Beyond that they go to 2 prims

I embedded an invisible ramp into the MESH object so the stairs will be easy to walk up no matter what size you make it.

When you change textures on the stairs use SELECT FACE and select the sides or back of the stairs not the stairs themselves so you don't loose the alpha texture on the ramp.