My truck has developed a low db whine (drone) from 20-22 mph. It started after I lowered the air pressure in the rear tires to 50psi. I can't tell whether it's coming from the drive shaft or from the rearend. Has anyone else experienced anything similar?

 

Raise the tire pressure again. If the noise goes away, it is tire related.

 

Agreed, probably the tire pressures seeing as that's what you touched. If you touch something and something happens, untouch it.

Where in Central Indiana are you? I'm in Terre Haute most of the year.

 

We're in a rural farming area about 70 miles north of Indianapolis.