When is a good time to change spark plugs on a newer vehicle?

Does anyone have a good idea if I should change my spark plugs for my 2005 Explorer Sport Trac? I'm sure it is recommended to change @ 100K miles. I'm currently at 57+K and was wondering if it would do me any good to change them now. I just would like to get more HP or MPG's if this would help. Thank youWhen is a good time to change spark plugs on a newer vehicle?well those are iridium tipped plugs they will last 100000 miles without really losing mpg or hp the only problem is getting them out of the head after 100000!!!When is a good time to change spark plugs on a newer vehicle?if your going to buy a better plug (im still not sure they save gas not sure) then go for it try it out but just pull one out unless its got build up on it or corosion then replacing wont make a diff either way not going to change hp unless urs is running bad u can change chips in them to gain hp but ur going to lose mpg gl hope this helps uWhen is a good time to change spark plugs on a newer vehicle?75K use best you can get...