Tires: 5th Wheel Tire loads/Upgrading, 5th wheel, highway speeds

Question
Current:
40' 5th Wheel, tri-axle, approx 17,500lbs, 235/85r16 Range E tires

Issue:
a few blow-outs at highway speeds, loss of pressure if the unit is sitting - I believe I am at the upper range of the load range capacity for E tires (3042 x 6 = 18252:  if I'm above 17.5, I'm very close)

Question:
I would like to move up to a Load Range F or higher tire.  Several questions:

1 - recommendation on tires that would be suitable in that size (Michelin XPS Ribbed only go to Range E...)?

2 - will I need new rims (current rims are rated for 80 psi only I believe)?

3 - are there any diameter issues I should be aware of (or, are all 235/85/16's created equal?

Many thanks, Dave

Answer
David,

1)  I'm sorry, but I work for a major tire manufacturer and shouldn't make brand specific comments.

2)  I think there is enough margin in the rims that you can use them without fear.

3)  No diameter issues - unless that particular manufacturer does something peculiar - so check before you buy!