They may also be less than 60kts
According to ICAO Annex 14, Volume I, Chapter 3, Nr. 3.9.16:
Recommendation.- A rapid exit taxiway should be designed [...] to enable exit speeds under wet conditions of:
- 93 km/h [50 kts] where the code number is 3 or 4; and
- 65 km/h [35 kts] where the code number is 1 or 2.
Cheers
hvogt