[lewisnc100]

Its probably not your tires or your brakes. There's a Technical Service Bulletin (TSB) out on this noise and it comes from the baffle plates behind the hub. Should have been easy for them to look that up since it applies to your model year.

I had the same problem, usually starts to make noise once the wheels warm up and the noise does not change much when applying the brakes. The baffle plates run about $20 each, one for each side. Unfortunately you have to remove the hub to swap the new plates in for the old ones, but if you're repacking the bearings anyway its no extra work. Some people just cut the rubber edge off the original baffle plate and that seems to work too.

Here's some of the details in the TSB (97-014A):

If a 1996-98 Pathfinder vehicle exhibits a high pitch squeal or whistle from the front hub/brake area, the cause may be the front hub dust seal. This noise, can be heard while driving next to a wall where the sound is reflected. The noise is also more likely to be heard after several miles with the front wheels at normal operating temperature. A countermeasure front hub baffle plate is available to resolve these incidents. The countermeasure baffle plates are modified to also function as dust seals.

Baffle plate RH 41150-1W400
Baffle plate LH 41160-1W400