Replace roof before selling rental house?

[Jack B.]

I have two houses that the inspector told me needed new roofs within a 1 and 5 years respectively. Well I've had the houses for 6 and 4 years, no leaks, knock on wood. 

Thing is I wonder whether I should replace the roofs at a cost of about 10K and 5K before I try to sell them or just leave them as is since not leaking? I have read in articles online that you don't really recoup the money, but I imagine it would make the houses easier to sell. I'd hate to have to spend the money, but if I have to...