Assuming you have 18" rims already?
Sounds like the tires you need then.
Old "new" tires even cheap won't always be a good deal. I ran some new never used but 20+ year old (even stored inside) goodyear 8-19.5 tires on my truck and they did fine for about 10,000 miles but then both rears started to loose sections of tread. The tires were free and served me well, but had I paid anything for them I would have been a little disappointed.
Grigg