Hi, I have a 1988 Dodge B250 Hightop conversion van. This van has a queen bed, solar panel, lithium battery and a lot of camping gear. Last year, discount tire sold me new tires and put 235/75r15 Cooper Discoverer AT3 4s 109T XL Load tires on my van. Upon reading today, I realize that these are only 4ply tires. I am googling but it appears these are actually the best tires made in my size. Does anyone have a tire that is Load E and 10 ply in this size? How dangerous is my current tire?