FIRST Issaquah Costco told me flat out - no cross border warranty on tires on batteries anywhere in the world.
SECOND Costco Mexico does not give road hazard warranty nor mileage warranty on any tire they sell. Eyeball to tire rack, Ensenada MX and Chula Vista, CA.
195 x 70 x 14" Michelin, exact same tire cost me $38.13 less each tire out the door nitrogen filled and spin balanced in Ensenada. Prices comparison was made 3 days apart. For that $38 each I surrendered the 95,000 mile treadwear guarantee, and road hazard. I am soon going to be so far from the US border for so long the warranty issue is a moot point.
Contact Costco Wholesale for verification if you wish.
A few items like hearing aids are cross-border warranty eligible. But not tires or batteries, or electronics. No item is refundable. With a varying exchange rate wouldn't that be a gas?
I loved the answer the manager of the Costco in Morelia gave me as to why a small flat screen TV was priced one hundred thirty two dollars more than the identical in Tucson. Before tax.
"This is not los Estados Unidos"
PS I saw Goodyear, Bridgestone and Michelin tires. I did not see Harmonious Hummingbird or Glorious Great Wall rags in the tire dept. Costco Mexico does have Kirkland Batteries. I did not check the price difference against US Kirland batteries.