My front tire on my Stumpjumper FSR started squeaking one day. I have seen/heard this happen on other Specialized bikes with the Hi-Lo hub on the front. Here is what I believe to be the fix to it.
This video will show you how to change the bearings in Stans 3.30 hubs, both the front and rear hubs. I'll also show you how to change the free hub bearings. This service is similar for all 3.30 Stans hubs but if yous are the HD hubs or road hubs I would recommend taking a quick look at the "ZTR/3.30 Hub Service Manual" at www.notubes.com (go to Help Center and look under Instructions).