Front end noise above 40 mph on 05 1500 Silverado
 

I have43,000 miles on my05 Silverado 1500 Z71 with 6 inch lift and 35' tires. I removed front air damnow a humming noise starts at 40 mph. Is it just an air noise or is there maybe a problem with a bearing or something else in the front end. I've had the lift and tires for 35,000 miles with no problems.