i am going to assume this truck is a pneumatic tire truck?
you are considering going to solid tires because of constant flat tires? or possibly a stability issue?

how am i doing so far?

well going to solid tires is definitely an advantage when having to deal with these situations. They do cost a bit more but in the long run you don't have to deal with the flats or instability.

IMO all pneumatic trucks should have solid tires on them ;o)
as far as how long they last? well if taken care of and the operator watches where he goes and takes care not to run over objects these tires can last twice as long as regular tires.
on a normal concrete warehouse floor the wear factor is minimal, now if it goes outside on pavement or rougher concrete they will wear out faster.

i have several customers that run solid tire pneumatic trucks and the ones that run in warehouse do not have to replace tires very often. But the other customers that run outside generally have to put a set on about once a year.

just my.02 worth :o)