At about what mileage would you expect to change the struts on a 2008 Kia Rio?

We live in Maine.

'Nuff said , about the winter!....If you don't suspect that you hit any hard bumps or slid into a curb or two, (which living in Maine I expect bad road conditions are nothing unusual to you-read that as -you KNOW how to drive!), I would get it to another shop for a second opinion , without telling them the other places conclusion first, if they come up with the same , then struts might actually be a problem. Ask for a guarantee on the repair & diagnosis.