Most of the string makers who make banjo sets make tenor banjo sets, though you might have more success finding them by mail order than at your local music shop (unless they're into banjos).

A quick Google on "tenor banjo strings" brings up not only retail results, but some discussion of the gauges wanted for Irish tuning (which apparently is low) versus standard tuning.

Here's some specifics from UltimateBanjo.com, a site that focuses on 4-string banjo:

Q What strings and gauges should I use on a plectrum banjo using guitar-tuning (D-G-B-E) what strings should I use ... Banjo.. Guitar???

You should use banjo strings, not guitar strings.

String gauges are very subjective. It really depends on the your playing and the sound you like to hear.

Personally, I use a little heavier gauge than most players: 26-20 wound -14-12. My banjo partner in the Southtown Strummers uses the same gauges but likes bronze guitar strings for the wound ones. He feels the sound is brighter. One of the best West Coast banjoists around is Dave Marty.   He uses: 24-16-12-11. They're pretty light but they work very well for him.

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Me, I play 5-string, but I know how to use Google.

~ Becky