Tires: Need a Sturdier tire, gawr, worse case

Question
I drive a loaded contractor van (Electrician). I have yoko Geolanders (rated 108 xl). The 235x75x15's with 44psi in them look too soft and they seem to be wearing on the outside. Is there an all season I could get with a heavier sidewall? I can't find an E load for my 15 in. wheels. Does anyone make an E load for 15's?. Would a switch to 16 inchers be my only choice? My '97 Ford E-150 has had the suspension upgraded.
Thanks,
Lee

Answer
Lee,

It sounds like your real problem is that the van is too small, and naturally, so are the tires.

I suggest you get the van weighed in the worse case and compare that to the GAWR's written on the placard.  That way you'll have a gauge about what you'll need to do!

And yes - 16" would be better!