At how many miles should I expect to change the shocks on my '05 Kia Sorento?

I have a '05 Kia Sorento which I love. It has about 48k miles on it which have been mostly highway and country miles. At how many miles should I expect to need to change my shocks? Seems like it has gotten a tad rougher of a ride over the last year but the tires are also only about 6 months from needing replaced, if that matters.|||3