The power wheelchair that has the highest weight capacity would be the Boss 6 Series Power Wheelchair which can be found here and allow users up to 600lbs.
Which power wheelchairs offer extra wide seats?
Which Power Wheelchair has Elevating Leg Rests?
Where are CTM Power Wheelchairs Manufactured?
What is the most reliable power wheelchair?
What is the fastest power wheelchair?
What is the most expensive power wheelchair?