what sizes did you input to the tire size calculator?
You can also go to tirerack and look at wheel packages. Input that your 14" wheel size and see what tire size it suggests for a 15" wheel. Just note that its close and there could be better options. When I went from 15" to 17" wheels tirerack recommended a 17" tire in the same width but was alittle taller then the typical 17" tire most use. no big deal in the end, just could have gotten a wider tire.