I recently went to Yakima, Washington for the weekend. It is where I was born and raised. The trees at my mother's house dripped on my truck to I washed it off, but I did not dry my truck for about two hours. (I got side tracked with social obligations) When I went back out to my truck it had BAD water spotting on the glass and left some on the paint as well. I dried it off, but it was too late. You could feel the crystal formations of the hard water on the glass from the calcite content in the water. At least that is what I was told caused it. Anyway when I got home . . .
I searched the forum and came up with the following thread.
waterspots on glass
Read the whole thing! I was particularly interested in the posts by BERVINATOR and BLOWNHARLEYFORD.
I decided to try Bar Keepers Friend (it is refered to in the thread as Bar Keepers Helper). It is available at most grocery stores and a great product. I have used it for lots of things for a long time.
I tried the White Distilled Vinegar routine and it did absolutely nothing. I soaked towels in vinegar and let it sit on the windows for 10 or 15 minutes at a time and scrubbed with it . . . Nothing.
Then I used Bar Keepers Friend on a sponge. I started out cautiously, which I would recommend. But I ended up being fairly agressive with it. Use enough water to make a paste that spreads very easily and use a circular pattern, rinse well, check and repeat as neccessary. I got my windows back looking just GREAT! I was so pleased.
Use it only on the OUTSIDE of your windows, NOT on the inside. That is where the tint is applied, and you can do damage to that tint coating.
Try it! I got just great results with it.