Mj: the Sterling I drive is a 33,000 2 axle truck, max load wt 13,000, [though I rarely get close to max wt] and it's been doing fine for more than 3 years now.
I watch the signs: if it specifies 3 axles or more [Ca, Tn, NC, Atlanta loop], I can be in the left lane, though I try not to. It seems...