Go to a 275/65/18 lots of choices in that size for a good LT load range E tire. It is only 10mm narrower I doubt you will even notice. Tire is a total of 1/2" taller, but it will only raise your total height 1/4 of an inch.
I still have not pulled the trigger. No hurry with the weather. I'll take a look at that size. Thanks for pointing out the missing lug nut. It won't roll out of it's cave without new rubber.