Knee pain -- possible solutions

I have had knee pain (left) for several years. I have been to several bike fitters and physios about it and still have no solution. My pain is on the top and front of the knee. My bike fitter noticed that my left knee goes out (away from center of bike) when I get tired. He suggested strengthening my core and increasing my flexibility of my hips.

Some things I have tried that seem to help include:

1) My left leg is smaller, muscle-wise, than my right leg. I was surprised that the bike fitters never thought of this as the source of the problem. I have started doing leg extensions with the left leg only. I started with 15kg and now am up to 45kg (6 sets of 8-12 reps of various weight). My left leg is increasing in size.

2) I roll my left leg's IT band and quad every day, esp. after rides. That helps.

3) stretching hips, quads, and hamstrings -- I have been doing that for months (each day) and it helps some but not as much as the above 2.

4) started working more on hip stretches and strengthening.

5) recently tried to pedal with knees in toward top tube and it seems to be helping (2 Dec 2017)

HED wheels (60s) & the difficulty of changing a tyre

Wow, I have never had so much difficulty getting a tyre onto a wheel as I did with HED wheels. I learned that in order to do get the tyre on successfully, I needed to keep the side wall of the distant side of the tyre down inside the well of the tyre.

Tyres that are relatively easy versus very difficult to get onto HED wheels (all are 25mm).

1) Hutchinson -- relatively easy but need tools
2) Schwalbe -- impossible to get on
3) Continental -- very difficult but doable with tools
4) Pirelli -- easiest of the ones I have tried; did not need tools