You didn't include the model number of the radios, but I suspect you're referring to Family Radio Service (FRS) / General Mobile Radio Service (GMRS) two way hand held radios. The FRS /GMRS types are limited to just 1/2 watt. Base GMRS type radios are limited to 5 watts. FRS is limited to Ch 1 - 14. Ch 15 - 22 are GMRS only, and require an FCC license to transmit. You can read more about FRS on Wikipedia
Many FRS / GMRS two way radios claim incredible distances on the packaging. I've seen some that claim 15+ miles. Given the low power (.5 watt) that they are limited to transmitting, claims such as those would be under the most optimal of conditions. I can assure you that you or I would never encounter those conditions unless we were in some sort of radio laboratory / testing space designed to obtain these crazy distances. In other words, even in optimum "real world" conditions; these radio should only be expected to work when separated up to only several "unobstructed line of sight" miles (such as across open water of a lake, along a beach, etc. The range of these same radios will be reduced significantly when operated indoors, outside between buildings, where blocked by rocks, trees, metal, etc. The only reason you may have reduced range could be due to a power level selector switch that has been set to reduce the output power of the radio. Other than that, I think you'll find a couple of miles is about all you're gong to get.