Expiring domains question

Hello,
when we buy expiring domain,do they lose their pr?

It really depends on what you do with the domain. If you just park the domain, it will eventually lose the PR. If you develop it into a similar site, and continue to build links to it, you should be able to keep or increase the PR.

When I build a site on a domain with PR, I try to use a similar title to what the site had before, and the domains usually keep the PR.

Hope that helps, that's just my experience.

is it a good idea to buy pr sites?