some fast diagnosis: Unless stepping on the brakes traveling in a straight line changes the noise to worse or better, it's not brake related. If the noise changes with engine speed, not travel speed, it's engine compartment related. Wide sweeping turns at 30-40mph with noise changes...wheel bearing or tires....usually the bearing. Still not sure.......
A really good shop will have a 'tool' that has four transmitters that are fastened near each wheel under the truck. Inside the cab, while test driving, they have receiver that picks up each transmitter's signal...which allows an instant match to 'see' where the sound is coming from. The transmitters can be moved around underneath and again driven until the transmitter that matches what's being heard is definite. Obviously, this isn't a free service....but it's fast and accurate.
Moving on.
1st. like above comment, swap wheels left to right, first front, then rear to see if your sound travels with the tire.
IF it travels, you have a tire issue..prob a belt. If the steering wheel pulses, it's most likely in the front. If you get a sensation in your seat while hearing the noise...it's in the rear. Did you get an alignment with the new tires?? No, then it could be off. Yes...they should have inspected bearings, tie rods, ball joints etc. before doing any alignment...you can't align worn parts. They should also give you a before and after printed out for your records.
If that hasn't found it, put the truck on a lift (best choice) or frame jack the truck and put up on jack stands so all four wheels can hang and be removed. Start the truck and put in 4wd. Now with an automotive stethoscope ($4 at Harbor F), go from driver front to pass front to pass rear to driver rear and place the stethoscope on the steering knuckle where the dust shield mates up front and on the rear at the juncture of the axle tube and dust shield. You'll find your 'waa waa' if it's a bearing. Clearly if one sounds distinctly different from the others, you may have a bad bearing at that location and the noise changes under load to what you describe. While up in the air and checking things with the stethoscope...check the drive shaft support bearing.
Usually, a wheel bearing noise is prominent when turning and quiets somewhat when returning the straight line attitude. A straight line noise that varies with the speed of travel would make a CV/universal my first choice to check out. Elimination of bearings has to be done first before pulling a CV/universal. Still not discovered, then check the pinion bearing for both front and rear.....also done up in the air, trans in drive all parts spinning with your stethoscope.
BTW, if no pulsing in your brake pedal when light pressure is used to put just enough tension to engage, rotors are not an issue. I'm not aware of caliper issues making noises, but you could be the first. Calipers in a state of disrepair destroy brake pads. Seized piston wears down the inside pad more and bad pins/wrong lubed pins or bad/wrong lubed slide hardware takes out the outside pads early.
A slightly out of balance or even out of round tire could also be your culprit! Not unheard of with brand new tires, just like a shifted belt is not out of the question in a right off the shelf new tire. Not on a Titan, but a diff truck, someone installed the rear shoes backwards, yes there is a difference in parking brake shoes f & r, and because of that, one was dragging making noise and since drums can oval out over time, there's an oscillation noise from it. One last noise maker.....a bad shock allowing a tire hop. The last two are pretty much last resorts when all else has failed.
