Walmart follows the book. They will not install tires that are not in the book for that vehicle, they dont want to get sued, not to mention you need almost no experience to get hired. I have gone there three times because they where cheap.
First time was on my Eagle Talon. Z rated stock tires. They could not mount because it was too low pro and didnt want to damage tires or rims after making me wait 3 hours, even though they where stock sized tires.
Second time was 265's on my stock rims. They made me wait 3 hours and once installed they put the white out instead of black and had to do it again.
Third time was 285's on my wifes Expedition. Thats only one tire size over for her vehicle. They refused to do it and acted like I was stupid and that they wouldnt fit.
Also there balance weights like to fall off, stay away from walmart for auto work!