You can also sew those wider bindings using the 1/4 edge of the quilt and cut your back and binding further away from the edge. This will give you a full wider binding. You will need to adjust at the corners so that your folded point will come out where you want it.
When I trim my quilts for bindings, and the bindings are cut at 2-1/2", I leave an extra 1/4" beyond the edge of the quilt so that the bindings are full.