I just looked at that Continental tire .It is on ebay ,modeling hub caps.
The picture  is so clear that the side wall would show cracks ,if there
were any there.  www.ebay.com   sale 260061744539  Now,I am not
complaining about blowing out tires.Not scared of them,either.Also, dont
think the weight of the Vanagon caused this,alone.My excellent pep boy
tires also inflate to 44psi,max.I inflate them to 39 front and 44
rear.Year round.The Michelins were inflated to 39front and 44 rear(tire
max),as I remember. I think it was age that caused this problem.I know
that motorcycle safty inspections will fail if side wall cracks are found.

The consumer product safty department in Washington DC was doing a study
on tire dry rot on the side walls.I called them a couple of years ago with
this exact situation, and found this out.Wanted to know if these michilins
were ok to use with the cracks,The study may be complete at this time.
They wanted to find out if this rot caused tires to blow out.They could
not tell me to not to use the tires because of rot.