Using a wheelchair outside an eruv on Shabbat

Hi,

One who needs a wheelchair may use it to wheel himself outside of the eruv; the wheelchair is viewed as the equivalent of his shoe. However, if the wheelchair must be lifted in order to cross a threshold, one should ask non-Jews to do it in a manner which will only violate rabbinic law; this may be done only in a case of need.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:90)

Have a great day,
Mordechai