Humming while driving

have ur wheel bearings ck

that is your transmission slipping. check the level and see if you are low

If it is a manual transmission, sounds like the front clutch plate.

Based on your description: 150K+left rear slowed down much quicker than the right +/ and the humming noise, there is a great possibility that the Wheel Bearings will have to be replaced.

Sounds like your wheels are not properly balanced,worn,or in need of
an alignment. Make sure all the tires have the correct air pressure in
them first,before getting them High Speed Balanced.Good luck.

Alignment will not create a sound by it's self. The most common cause of humming (especially if you have an agressive tread design)is a wear pattern in the tires...check for that or rotate the tires around & see if the noise changes. If it does then you know it's in the tires. & Not always, but most of the time a bearing noise will increase or decrease in intensity if you load up one side at a time by doing 35-50 mph & turning slightly to each side.

My 2003 Impala did this after I replaced two and moved the old back ones to the front. Really audible difference though the treads feel smooth and theres plenty of tread (bridgestones). Same 4 tires but the original back tires are staying on the back now with at least a year worth of wear left.

we have a 2003 saturn vue which we installed new tires on and we noticed a noise about 6 months afterwards. it sounded to my wife and i to be loud road noise from the tires. the car was driven for 6 months and we decided the noise was annoing. had the tires checked only to find it was the left front wheel bearing which was replaced and stopped the noise.

check your tire tread, it may be worn in a choppy pattern and causing the noise. if your tires are smooth, then you have a wheel bearing problem

it could be the bearings werent packed enough with grease or it could be the tire making the noise.