General What should % humidity be in Garage?

[JDDogg]

Please help!! . I have a 1981 Spider that I keep in my garage in the winter. The temperature is from -8deg C (17.6F) to + 12deg C (53.6F). My RH% (Humidity) is reading 70% - 75% and Iam woried this is going to cause rust.

Please advise what I should do.