The outside of the bend is stretched thinner while
the inside goes into compression... but Cab is correct
on the numbers.... a inspector can check anywhere he
wants to check with a sonic checker... they tend to
check some straight areas for the base thickness and
will check some of the outer radius areas if they can
get on it square with the checker... I was asked
the first time I certed my car what the material was
and what wall thickness in different areas and why
I did a couple of things.. once I told him why I did
it that way, he said... thats a real good answer..
it wasnt just show up and they stick a sonic checker
on it... at that time my car was a 7.50 cert and it
passed with flying colors(since then they changed
some of the requirements)