If it is bad enough you can hear it rumble as you drive the vehicle otherwise you can jack up the rear of the vehicle and support it safely, strip the calipers, brake pads and rotors off, grab the axle hub and try to move it up and down. There should be little or no up and down movement, in and out play is okay. Notice also if you have leaky axle seals, that would be another clue. If you have excess play in the axle, you probably have a worn out axle also. The axle bearing rides on the axle so when an axle bearing goes, so does the axle.
Check related answers. There are several responses and are quite accurate.
No. That is a factory sealed bearing.
no the hub and bearing are 1 peice and pretty easy to changs
35mm
Replacing a wheel bearing in your Chevrolet blazer will cost approximately $175 per bearing. You can save $125 by doing the work yourself.
34 mm
36 mm
A front popping on the left of a 98 Blazer could be the brakes, steering, or wheel bearing. Check all three to find the cause.
Worn right front wheel bearing.
Yes it can be. I think you need to replace the whole hub assembly
How to Remove the Steering wheel From a Chevy Blazer 2001
36mm. You will also need an 18 mm box wrench to replace the bearing assembly.