tuna,
Your OEM tires on your truck were 245/75/16 "E" 3042 lbs at 80 psi. You can use 265/75/16 "E" 3415 lbs at 80 psi. The Michelins work well with your present wheels/rims. It does NOT bulge the tread in a convex shape at all running them on the GM OEM 6.5 wheels. I've been running the Michelin LTX 265/75/16 "E" M&S tires on our 2004.5 since 2006 when I replaced the Bridgestone OEM that were bald with less than 30K on them. The 265 Michelins give about 100k in miles if you keep them at 80 psi.
I know that for a fact as we had them on our previous 2500 GM truck for a little over 100K and they still had 3/32 tread left but it was time to replace as they were 8-1/2 years old. Just replaced the 265 Michelins on our present 2004.5 Chevy 2500 D/A CC LB 4X4 last fall before we pulled the 5th wheel down to Florida for our annual and they had just under 100K on them but they were just under 8 years old and tread was down evenly to approx 4/32 average. Both trucks are/were only used for RVing with either a heavy Lance TC on or our Carriage 5th wheel 12,840 lbs scale weighed ready to travel behind and a few time with our TT (now sold) behind. I'd even sent pics of them 2 days before being replaced to a member on this forum so there is closeup picture to backup.
I posted this info in another thread so I might as well do it here too. Someone who knows pickup tires very well as they have been doing all the city/area department's pickups and cars plus most of the local businesses vehicles for nearly 30 years now. Most of their customers agreements state only Michelins to be used and he can tell you what mileage and life they get from the Michelins.
The tire businesses name is: Z-Tire, phone no. 616-846-1600 and the owners name is John and who you want to talk. to. Alex may answer the phone and is knowledgeable about it but John knows the entire info and history. I do not have any interest of any kind or have any family interest in their business as I've only been a customer of theirs but I DO know the facts and the vast direct tire education John has been privy to professionally for over 30 years now. He was spot on for me also and can't thank him enough. Pick his brain it sure can't hurt as the man is brilliant about tires and why! Not a solicitation in any way as you are over 2,000 miles away but may be very helpful to you coming from the horses mouth as many from the region constantly ask him for his info, knowledge, or advice. A good honest man!
What you buy doesn't mean anything to me as it's your truck and money and i'm just offering you some info to consider or check out. Good luck with your decision wahtever.