In article on this page
http://www.airwar.ru/history/locwar/...su17/su17.html
It is written that on planes Su-17 6 locks holders for bombs i.e. on 1 hardpoint=6 bombs of calibre from 50-100 kg could to be established. But also it is written that in the conditions of strong heat and a hilly terrain by these planes they were not applied since these planes bore 2 more fuel tanks on 800 litres.
Unfortunately about 250 kg of a bomb and this plane Su-17 I have not found exact data, but it is possible to assume the following: there were 4 locks holders of bombs for 50-250 kg of bombs and 2 locks holders for 500 kg of bombs. Judging by load-carrying capacity Su-17 it would be possible assume that it could to bear 4 or more 250 kg of a bomb.
Drawing Su-17:
http://www.airwar.ru/other/draw2/su17_z.zip
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