And have a higher weight capacity than one 245/75/16 E range tires
The 315/70/17 I have are D range and have a 3119lb rating
Hell the 225/70/19.5 F have a 3640lb rating which is less than a 285/75/16 E range that has 3750lb rating
Yep. A load range E tire is good to a maximum pressure of 80 psi, load range D is good to 65 psi, C is 40 (I think, haven't bought any load range C tires for a long time), and XL tires are good to 50 psi. Tire weight ratings come from their size and load range. A 265/75R16 tire will have the highest load rating in load range E followed by D, XL, and C respectively. However, as you add more volume and contact patch to the tire, the weight rating goes up, so a 285/75R16 in load range D would probably have a higher weight rating than a 265/75R16 in a load range E just like the 305/50R20 does in the XL rated tire.
This scares me because ive had plenty of nails in my winter tires that ive left in for weeks and its never cause a blow out like that. Coincidence maybe? Or like stated they are the correct load range
Your winter tires must not have been losing air. If a tire gets low, it heats up faster and makes the tire weaker. I'm sure the roads are also hotter right now than they are when you run your winter tires which doesn't help the tire any either.
Well regardless 4 different big chain tire places refused so it's obviously a common trend
That's more of a CYA legal/insurance thing than it is some sort of law. Tire stores are stupid about this in my opinion. If a tire meets or exceeds the weight rating of the stock tire, I see no reason why they shouldn't mount it on your wheel.