Is My Shaking Tire Going to Explode? Tire Separation

We were driving along and the car started to shake. Why? Because our tire was separating. It was a classic case of tread separation. This wasn't really visible to us in general, but we did notice a slight bump in the sidewall of the tire. Bumps in the sidewall are also a problem, according to one website we looked up on the old iphone a bump of over one-eighth of an inch (i.e. a visible bump) is a problem. We had no visible bump.

Shakey Car From Wheels = Separation

Fortunately the shakes got so bad that we decided to change to the spare tire. There were gaping holes in the tire tread!

So, we got some new tires. It will be interesting to see if/how the summer tires affect the mileage now that we've got some real data.