Have the alignment checked at a local automotive shop.
So it can wear out the outer tread faster thus causing faster front tire wear which will help to sell more front tires.
60% tread wear.
tell the make and model of tires, the size and type of vehicle as well as the tread wear temp and traction off the sidewall. how many miles on these tires. are all the tires worn evenly front to back as well as side to side? Thanks.
Overinflation.
Completer wear of tread surface -(creating an unsafe tire ! )
There's several types of tire wear, I'll list a few of the most common: Low tread inside outside with good tread in the center = Too low air pressure. Low tread in the center with good tread on outer edges = Too high air pressure. Heavy wear on inside of both tires = camber and/or toe adjustment out. Heavy wear on outside of both tires = camber and/or tow adjustment out. Feathering or choppy wear = poor shocks and/or toe out of adjustment and/or unbalanced tire/s.
Many tires have tread wear indicator bars molded into the tread. When the tread is worn down to where you can see a solid bar of rubber across the width of the tread, it is time to replace the tire.
2/32
The humming noise is dependant on the road surface/ tire tread and tire wear. If the tires are scalloped or feathered they will hum. Vibration may be a problem in your suspension or the balancing of one or more of your tires. You can run your hand over the tread (front to back and back to front) if it is wavy or the tread feels jagged/ sharper in 1 direction, you need suspension work and/or an alignment.
So the tires will "wear" evenly and you will have longer "tread-life"
As a general rule, you should replace your tires when the tread wear indicator mark is equal to the tread (The tread wear indicator appears as a raised triangle, or the letters TWI on the side of the tire). All ATV tires have a different tread life, depending on the application they are used for. And when used in applications they are not meant for, tires will wear more quickly. For instance, using a mud tire to ride on the road will wear out the tire much faster than using it in the mud.
The wheel alignment is off, probably the camber.