I own a 98 4x4 LS Blazer S 10, today driving on the highway I start hearing a humming noise between 65 and 70 mph. Have new sat tires, and today I had my blazer front wheels align, once I slow down the noise stop around 35 and 25 mph. I need help

 

Could be a number of things ranging from the start of a u-joint failure, a wheel bearing failure, or it could possibly be that your front axle is partially engaged. Does the noise go away when you put it into 4HI?

 

It could happen, the front axle possibly partially engaged because one day while I was on he highway I saw the 4hi switch was on. How that happen I don't know?
Any answers and yes it did stop making a humming noise for now.

 

Note on Swartlkk's sig: Common 4x4 problems.. takes you here

If you need more, do a search with the simplest terms, like 'goes into 4hi' or '4wd engages by itself'

Hint: the google engine uses a more sophisticated algorithm.. type

'why does my ______ {and} site:blazerforum.com'
If you want info from all possible sites, type 'why does my blazer ______ '

IIRC this came up recently and the problem was in the switch itself.

Note that this doesnt mean there's anything specific. New/different tires reflect reflect surface textures differently, depending on tread pattern etc.. the deeper the tread, the louder they USUALLY are for a given pattern, depending on siping depth {look it up, wont explain here}. Not to mention the STYLE of tread.. you already know that off-road tires are noisy, right? Hope you do.