Awaz,
First thing, does your bike have spoke wheels or cast wheels?? If they are spoke then you will need tubes. If they are cast aluminum than they are tubeless and only need to have tubeless valve stems installed to get them back to original condition.
I have seen pictures of the 80 model KZ 250 LTD with spoke and cast wheels so they must have come with both.
Now as far as tires, go to oldbikebarn.com, they have several listings of tires for the 80 model KZ250 LTD. The front tire is a
90/90-18" & the rear is a 120/90-16". Hope this helps.