I thing something I am doing different in radius, may be the radius unit is different.
double radiusInMiles = 0.2;
double radiusInKm = radiusInMiles * 1.60934;
double lat = 53.342429;
double lon = -6.259931;
double kmInLongitudeDegree = 111.320 * Math.cos( lat / 180.0 * Math.PI);
double deltaLat = radiusInKm / 111.1;
double deltaLong = radiusInKm / kmInLongitudeDegree;
double minLat = lat - deltaLat;
double maxLat = lat + deltaLat;
double minLong = lon - deltaLong;
double maxLong = lon + deltaLong;
53.34532610171017 -6.255088077248368 53.339531898289835 -6.2647739227516315
Hope It will help our other friends too.
Please let me know if we can do same with radius.