I think someone may have misinformed you about how tire load ratings are figured. The system is pretty much universal, as virtually all tire manufacturers use the same ratings, regardless of where they are sold. I'm thinking that you're looking at the tire capacity rating, which would read "tire max load XXXX lbs/XXXX kg at YY psi/YY kPa. While this does indicate the maximum load a tire can safely handle, it is not an indicator of the tire construction, or whether it is designed to hadle tha max load for an extended period of time. That's where the ply ratings come in, which are the same for any country. While it is possible to have a P rated tire to have the same max load as an LT of the same size, the P tire will not last long under those max load conditions. Most P tires are rated at 4 ply, though some are 5. LT tires start at 6 ply (C range) and can go up to 12. Your truck would have had an 8 ply tire OEM. I've personally seen what happens when an underrated tire is used on a vehicle that cals for a higher load rated tire, even though the max load was the same. The lighter ply rating tire either wears out early, or in most cases, simply fails.
