Goodyear wrangler LT tires from Walmart.

I haven't purchased the tires yet but I like the price, country of origin (U.S.) and the tread design. These are Wrangler Trailmark tires, Trailmark being a Walmart brand, that are sold in Canada and the U.S. but when I questioned the warranty I was told that my Canadian purchased tires would probably not be honoured at U.S. Walmarts. Did not make sense to me, so I e-mailed Walmart with the warranty question and received back this response -- "This question falls outside of our writing guidelines and won't be posted--we hope you'll submit another question.
Any idea if this is a common practice at non-traditional tire stores like W.M., Sears, Costco etc.?
Thanks,
Warren.