I have some of those Vail ? tires on a cargo trailer I just bought.
I have noticed the same bulge you mentioned, also the tires seam to be wearing nicely.
On another note there is a recall on a certain size of those tires. I was able to check and mine were not affected, Mine are 14 inch and I think the recall was for one specific size in 15 inch.
I'm sorry I can't help any more but I don't remember where I learned of the recall. If I remember correctly I contacted the importing distributor and they returned my call with the info that my tires weren't part of the recall.
Google the tires name and you should get more information.