I wear orthotics for overpronation/bunion. should my shoe heels be no higher than 1 1/2 inches or less?

Usually < 1 1/2 in: Usually a heel height of approximately 3/4" will be an appropriate height. There are some custom orthotics that can be made with an adjustment in the forefoot that can be adjusted for a higher pitched (higher heel height) shoe; however, 1 1/2" is getting to the end range for that. I still would not advise a long period of standing or walking in a shoe of that height with or without an orthotic.

Yes: The higher the heel the more unstable your foot will be.

Yes: Anything higher leads to other problems like friction and instability.

Correct: Wearing a high heel forces the toes deeper into the toe box, and most of these shoes have narrow toe boxes. This will cause a bunion and hammertoes over time. If you already have a bunion, it can make it worse. At the very least, it will aggravate it more! Orthotics can help to prevent the bunion from progressing, as well as controlling pronation--they're only effective in the right shoes!

Orthotic for bunion: doesn't stop bunion form progressing, it may slow it down somewhat but bunion is a genetic issue and wil ltake its course. What you have to understand is that a high heel shoe may progress the bunion quicker then a flat shoe but an orthotic in any shoe will not stop bunion from getting worst. If you know from you family how the bunion progressess then seek help with a podiatrist for suggestions.

Yes: Over pronation can be lessened with well constructed neutral casted orthotics. The problem is that as the height of the heel increases the less likely an orthotic will help let alone fit into a shoe with a heel > than 1 -1 1/2 inch height.

Correct.: The maximum recommended heel height is around 1.5 inches as you stated. Once you get to a 2 inch or higher heel it distorts the foot and can do damage, especially toward the ball of the foot. A bunion is a complex deformity and often the result of poor footwear choices over time. Heredity also plays a role in the formation of a bunion.

Flats are best: Flats are best for you. Your orthotics work better and your bunion will do better