Regardless of what type of hurdy gurdy it is you have, the main thing is, how do you want it to be tuned, and how loud you want it.
Please be aware, that hurdy gurdies are a family of instruments and generally far from being as much standardized as violins.
Here is a list of Standard tunings. Other than standard tunings are possible, but only usefull if you need them, like for being in the perfect range for your/your co musicans singing or instruments. An instrument is usually played in all keys where there is a drone at the root or fifth of the root.
General information on strings for the hurdy gurdy can be found at the Strings page.
playing in G/C (and D and F)
This tuning is the most common one. Nearly all original compositions of the 18th century are written for this tuning. This is the traditional tuning in the Morvan and Auvergne in central France. Low drones in G and C, playing G and C major, minor, dorian, mixolydian, etc... Since it has a buzzing drone in middle c' with a capo to d' it can also be played in D and F. One advantage of the G/C tuning is that the relation between pitch and key positions (note names) corresponds with the one of the piano.
Traditionally both chanters are tuned to g' but it is possible and practiced to replace one with an string one octave lower.
playing in D/G
This is the standard tuning in the Berry in central France. Low drones in D and G, playing D and G major, minor, dorian, mixolydian, etc... It has a buzzing drone in middle d' and usually no capo. This is the best tuning for the "french" dance music. It is very brilliant and the balance with the pipes (in low D) is better than in the G/C tuning where the pipes usually drown the hurdy-gurdys.
Traditionally the chanters are tuned in octav-paralells, in d' and d".
playing in A
this is the hungarian tekero tuning, with melody in E and drones in A. Playing A major, minor, dorian, mixolydian, etc...
Today tekeros exported from Hungary are sometimes set up in (G)/C.