Zone listings can vary. I have some here in zone 5/6 which are listed for 7. I will generally error on the side of caution.

Microclimates make it difficult to say for sure what will do well in a specific area. Hortico has a good zone listing, I've had good luck with the roses they claim to be hardy.

The information shown in HelpMeFind is usually derived from the producer of the rose. But for many older roses, such information is based on the experience of rose growers as reported to HMF. If we don't have any reports of hardiness, an educated guess is used depending on the classification of the rose. By all means, if you have experience different from that reported on HMF, feel free to report it. You will be doing a service for other rosarians.

Rose hardiness is not a simple, single-variable concept. Under the USDA hardiness zone scheme, coldest temperature is intrinsically variable. Zone divisions are based on average low temperatures. Marginally hardy roses may have different survival rates through cold winters in the same USDA zone, depending on factors like snow cover, timing of lowest temperatures, and, worst of all, spring freezes.

For example, a rose that consistently survives a Zone 5 winter with ample snow cover (a great insulator and protector) may perish in Zone 6 even if the low temperatures were not as cold as Zone 5 because of bad spring freezes (low temperatures around 15℉/9.5℃, well above the lowest average temperature for Zone 6) that occur just as the rose is breaking dormancy and putting on its vigorous, young, tender spring growth.

One of the best sources of hardiness information is to check the GARDENS tab for a rose to see if any of the gardens listed have a climate similar to your own.