San Francisco’s collection of 32 antique fire-fighting vehicles is probably one of its best-kept historical secrets, all in the care of the nonprofit Guardians of The City. Want to see a “hose cart” that saved San Francisco from flames in 1850? They’ve got it. How about a 75-foot “water tower” on wheels, used to douse the 1906 fire following the earthquake? You bet. Maybe take a trip down memory lane with a 1958 cherry-red fire engine? That too. Here’s the catch: You can’t see any of the vehicles because the collection is essentially homeless. Guardians of The City is pulling the proverbial fire alarm and calling on San Francisco to find a home where people can visit this beautiful vintage collection. The group will present its dilemma to the Fire Commission on Wednesday night.