Compressing Google Maps Tiles

I'm looking for a way to compress the tiles from a Google Map (which I've already done) and then somehow replace the old tiles with the compressed tiles. This is how a tile looks in the code, for example:<img src="http://ift.tt/1Ey1fvl" draggable="false" style="width: 256px; height: 256px; -webkit-user-select: none; border: 0px; padding: 0px; margin: 0px;">

The reason I want to do this is because Google PageSpeed Insights keeps complaining:

Should Fix: Optimize images Properly formatting and compressing images can save many bytes of data. Optimize the following images to reduce their size by 245.2KiB (17% reduction).

(And all of the images it wants me to optimize are from the map.) I haven't been able to find anything googling around, so I don't even know if it's possible to do what I'm asking. Any ideas?