when to change spark plugs on 2007 Jeep Commander

When do the spark plugs need to be changed on my 07 Commander with 39,000 miles?

Asked by for the 2007 Jeep Commander
100,000 miles
Owners manual says to change them every 30,000 miles
2 answers 2 comments
Here is an online copy of your owners manual: http://www.jeep.com/en/owners/manuals/index.html
Look under the maintenance section.
Thanks for your help!