I have a White GT-1855 and when I did it I used the orange hand pump at Harbor Freight and got the valve stem to the top, took the cap off, took the valve core out and then filled the tire 75% full, put the valve core back in and put air in it.
I put a cable tie on the end to keep it on the valve. I can't remember now if you have to jack it up or not to fill it. Would think it would be better to do.
I used the -30 or whatever washer fluid. Using plain water is probably bad if you are in a colder climate.