800s + same old story

Firstly, this is getting old. I got a flat tire this morning. This is getting really annoying. I know it is partly my fault but I suspect that it is mostly because tires on this bike are s**t. Really low quality. I found awesome tires I would like to get but then the tires might be worth more than the bike:) But I work for a company best known for its tires so I might figure something out.

Now workout. Plan w/u 2.5miles, 5x100 w/ jog btw, 6x800 @ 5k pace w/ 200 jog, c/d 2.5miles
My 5k got adjusted to 19:45-20ish, so 3:9-3:12 for 800.
I was little worried about how it will go after hard-feeling workout on Friday and with only 200m jog btw. But when I did 1st at 3:08 I knew I will be ok.
It was more humid than last week but seems I am getting accustomed to it although I was sweating like crazy and had hard time breathing during the 4th one.
Well I am not sure how it is supposed to feel though. Hard, easy, somewhere in the middle? Hard at the end? I do not know.
I did 3:08, 3:08, 3:07, 3:07, 3:05, 3:04.
Does this also happens to you? You know the last repeats should feel harder and one should work harder to keep up the pace therefore I try to work harder to keep up the pace and end up running faster than I am supposed to.
I am satisfied and getting my confidence back because it felt good and controlled.

I did weights afterwards but no swim to loosen up.