I've had the Kirkland Signature LT tires on my '85 for close
to two years.  I've put 30,000 miles on them, including two
round trips to mainland Mexico, where they had hard use.

They've performed flawlessly!  Not even a single flat & they
still have enough good tread that they may carry me to Mexico
& back this winter.
They are meant to be inflated to up to 50 psi.
Can't beat 'em, especially considering the low Costco price.

Phaedra