New rumbling sound from truck, does not seem to be engine or exhaust?
My 2006 Toyota Tacoma has started making a light rumbling sound when rolling. It starts at about 20 MPH and stays with me at any speed from there on in. If I slide into Neutral, the sound continues unchanged, and if I rev the engine in neutral, the sounds from the engine is completely separate (and quieter) that this sound. The best I can compare it to is going over a rumble strip, but only about 10% the volume. I can feel a slight vibration in the floor as well.
The tire tread is good. I haven't checked pressure yet but the tire pressure idiot light on my dash hasn't come on.
Last weekend I made a long trip (about 400 miles) on Saturday and picked up a yard of moist mulch (which is right at the payload capacity) on Sunday. Not sure if either could have caused this.
Could it be poor alignment or balance, or something worse?