Index: trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java	(revision 17506)
+++ trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java	(revision 17507)
@@ -652,4 +652,6 @@
          * accessed when looking for tiles outside current zoom level.
          *
+         * The value should be sum(2^x for x in (-5 to 2))
+         *
          * Currently we use otherZooms = {1, 2, -1, -2, -3, -4, -5}
          *
@@ -1318,4 +1320,9 @@
          */
         private void overloadTiles() {
+            /**
+             * consult calculation in estimateTileCacheSize() before changing values here.
+             *
+             *  @see #estimateTileCacheSize()
+             */
             int overload = 1;
 
@@ -1584,4 +1591,9 @@
         }
         if (getDisplaySettings().isAutoZoom()) {
+            /**
+             * consult calculation in estimateTileCacheSize() before changing values here.
+             *
+             *  @see #estimateTileCacheSize()
+             */
             int[] otherZooms = {1, 2, -1, -2, -3, -4, -5};