Last night I noticed that my front tire had 7-8 bumps spaced along in the left half of the tread. Several of these were very soft like the tread was bubbling up. The tire has close to 20K miles on it and there appears to be more tread available (it's not down to the wear bar yet). I am aware of the uneven tire wear inherent with these bikes. There is some uneven wear, but it's not excessive. This leads to my question. Is this normal for Avon tires nearing their end? This the first Avon I've worn out on the front. When the stock dunny wore out, there was significant and obvious left-side wear with some cupping. Is the bubbling I'm seeing on the Avon just a different symptom of the uneven wear or cupping?