I'm glad to see Lexus equip the overtrail models with a good versatile tire. They will come with Toyo Open Country A/T III 265/70r18 tires.
Here are some additional specs from Toyo:
Diameter : 32.6"
Width : 10.7"
Weight: 51 Pounds
Tread Depth: 16.4
Revs/Mile : 636
(From TireSize)
Sidewall : 7.3"
Circum. : 102.4"