I'm afraid that Lazy Load + WP Tiles is not going to work. WP Tiles uses a div background image to show images, while Lazy Load lazy loads images that come as a <img> tag.
There would be two ways to work around it, both being quite involved:
1. Make WP Tiles use images instead of divs with background
If you modify the tile template in the JS (in wp-tiles.js around line 72) to use an image instead of a div, you could then further hardcode the lazy load data in there:
<img src="[insert the placeholder img url/data here]" data-lazy-src="[insert wp-tiles image gere]">
2. Create a lazy-load script for WP Tiles
Google around for lazy load div background images. You'll find scripts like this one. Then you just have to change wp-tiles (same spot in the JS) to set the background image in a data attribute.
Good luck and report back if you had any luck! Maybe it's a neat feature to have for a future version of WP Tiles as well :)