For ST, I'd go with the Maxxis M8008 mentioned above. Discount Tire sells them, but you would need to order them. And the advice to have them balanced is good advice. These tires have a max speed rating of 65 mph.
For LT, check out Goodyear Cargo tires. If you are going LT, be sure that the load range is the same or better than your OEM tires. You also need to check for clearance as the LT tire may be slightly larger in height and width.
You can address these concerns by going to
tiresize.com They have a great tool to compare tire sizes and a way to visualize the difference. So you would plug in your current tire size and the size of the one you are considering.
I looked at them just now and see that they come in a size close to yours - but a little shorter - Size: 225/70R15C. Use that link to see the difference. The load range may not cut it though.
I almost bought the cargo tires, but thought I'd give the Maxxix a try. so far, so good. Good luck.
Experience without good judgment is worthless; good judgment without experience is still good judgment!
2018 RAM 3500 Big Horn CTD
2018 Grand Design Reflection 303RLS