doesnt surprise me mixed advice from manufacturers, our advise came from michelin but dont know what one is correct tbh, one thing to think about though, i sold my old car about a month ago but before i did i had a puncture so put the full sized spare wheel on,,, first time it had been used since 2001 when the car was built,,, could tell by the dot ( date of manufacture ) on the side of the tyre,,, and i couldnt beleive that it still had the full and correct tyre pressure from day one,,, amazing,,,, and it was fully inflated to 31psi,,,, now i know it has to be fully inflated so you can use the thing but after 11 years it lost absolutelly no pressure from -20 degrees to + 30 or so year in year out,,,, i put it on the car and ran it for 1 week,,,, pretty amazing isnt it and i tell you it had no tyre cracking or anything,,, looked like it was bought the day before,,,, it was a continental 195 - 65 - 15 h,,,,,,
maybe need to do a bit more research on the pressures buddy as thats 2 diff manufacturers saying 2 diff things,,,,, but you can actually phone michelin , goodyear etc directly and speak to their tech dept,,,,, guess there numbers will be found online,,,, may answer the quest if you phone maybe 3 of them as the advise i was given from them was around 4 years ago
cheers