Yes LT. thanks.Cooper don't make an ISO-Metric 285/65/18 Discoverer AT3 XLT tire. So no, I cannot recommend a RCTIP for those non-existent tires.
If, however, and I'm just guessing here, you mean the LT-Metric LT285/65R18 125/122S Load Range E Discoverer AT3 XLT tire, then yes, I can help you.
The RCTIP for the LT285/65R18 125/122S Load Range E Discoverer AT3 XLT tires on your LX570 is 37psi F/R.
HTH