We need a little more information. Did you buy it new? Front or rear bearing and how many miles are on your Stratus. You could call your local Dodge dealer and ask but, don't just accept no if it is low milage. Ask them what caused this. May be a common problem.
Stratus had a problem in 98 with a low frequency rumble or gear type noise coming from the front of vehicle between 50 & 75 mph. Noise was not throttle sensitive.
Diagnosis: Verify sympton/condition is present, inspect front hub/bearing assembly build code datelocated on the outer edge of the hub nut cavity. If the build date is from 6/11/97 through 8/12/97 there is a recall. Yours could fall in this even though it's a 99. If build date did not fall in this range futher diagnosis is required. Good luck