Alignment and Tire Wear

After nearly 40k miles, the original BFG Long Trail tires on my 2006 SE 4x4 were well worn and very noisy. I am no tire expert, but both the Nissan dealer and local tire shop noted that the tires were "badly cupped." Since the tires were well worn and winter was approaching, I elected to have them replaced at the tire shop, and then had an alignment done at the dealer (so that they could also install the cam bolts). However, I thought that cupping was typically due to poor suspension, though I'm not noticing any obvious suspension problems when driving. Obviously, I want to ensure that the problem which caused the Long Trails to cup is rectified so that I don't ruin $600 worth of tires (and yes, I do rotate on a regular basis).

The noise that i was noticing was a rotational noise, a quiet "thump" sound that would change with vehicle speed, and was especially noticeable under 50mph. The new tires did eliminate the noise.

I do a good bit of highway travel and it's sometimes a challenge to avoid bashing large potholes in the winter time. How well do the second generation Frontier's hold their alignment?

Below are the before and after numbers for my alignment. If I need to look elsewhere for the cause of the tire cupping problem, I would appreciate the feedback. Thanks.

BEFORE:
http://i46.tinypic.com/14aiil0.jpg

AFTER:
http://i48.tinypic.com/i2lzbt.jpg