Originally Posted by iluvlcy
they may have been indents instead of bubbles i should have taken a picture.
I kind of had a feeling that's what it was going to be. If they were indents, it's called undulation, and they are normal for radial tires (we need to make sure you have radials though).
An undulation in simple terms is just where the tires body plies overlap each other, and this was done in the manufacturing process. It's purely a cosmetic thing and doesn't hurt the performance or life of a tire.
The easiest way to see if it's undulation and not a broke ply cord(s) (which would bulge outwards) is that wherever you see the undulation (indention), it will also be on the opposite side of the tire in the same place. Just reach around the tire to the opposite sidewall and you should feel the indention there too.
If you have broke cords (a bulge), it will just be at the place of the damage...and not on the opposite side too.
Just about all radial tires have undulation, but on some it shows up more than others.......and you may have it in more than one spot too. I've seen some tires that had seven undulation spots on them. Two to three is the more norm though.
I have to explain undulation many times a week to customers who think their tires are going bad.
Edit: Here is a Rubber Manufacturers Association file about undulation