I've had a long debate about this.
I think the concensus was that a group of tramps was known as a Scuffle.
(Sundayturkey has the biggest mug of tea, Thu 2 Jul 2009, 17:54, 1 reply)

I sort of like
passle..

a passle of tramps..... scuffle is a bit too obvious and collectives rarely are...

or maybe 'honk'

a honk of tramps

or cramp

a cramp of tramps . . . .

that's it, I'm submitting 'a cramp of tramps'

betcha there'll be loads in on this...
(The Cats Twat, Thu 2 Jul 2009, 18:02, closed)

Suggestions
A cackle of tramps.

A richness of tramp.

A drift of tramps.

A streak of tramp.

An army of tramps.

An intrusion of tramp.

A business of tramps.

A plague of tramp.
(DeactivateThisDisaster No., Thu 2 Jul 2009, 19:06, closed)

I vote for

A drift or a plague


Beautiful tale BTW!
( @><|= w0nu!) or cunt to my friends, Thu 2 Jul 2009, 22:17, closed)

Possibly
An aroma of tramps
(badgerlikespeed, Fri 3 Jul 2009, 9:15, closed)