Why new tyres causes a humming?
Tire noise causes; also referred to as tyre hum or roar is a bug in its design features rather than the wheels being new. Your senses must be fully attuned to any sort of constant input, including the sound of original truck tyres.
In fact, the new wheels may be louder but chances are such that they give sound of a different frequency as compared to the old pair. We’ll look at the details as why new car or truck tyre creates a peculiar humming and possible preventive measures.
The tyre assembly
Tyres are a composite of three primary components namely rubber, tyre tread and internal reinforcing bands. Better road grip or traction comes with a softer rubber compound however they wear out faster.
A 100 percent smooth racing tyre puts most of the rubber on the road but the ability to shun water away from the tread is less. Strong supporting bands prevent the circular shape but they don’t allow them to deform; expand or contract to fit the surface condition thus raising threat against safe and smooth driving.
For starters; tyre noise isn’t the sound of the wheels in contact with the road. Physics say that sound isn’t a constant stream of energy but rather a constant compression and decompression of air molecules.
Carefully note, if one of your truck tyre tread block hits the road surface at low speed, it’s noiseless as air escaped from between the road as well as rubber in between the grooves (also known as tread blocks) without any compression.
At high speed however, similar fraction of tread compresses the air which expands the rubber block. When the next block takes the place, air compresses again and the cycle continues resulting in constant roar or unusual humming.
The rubber compounds
Hardness and softness of tyre’s rubber compound is crucial to determine noise because sturdy rubber composite compresses more air than softer one. Take example of dropping a large book flat on the floor and another one encased in a pillow. Pillow; as we know can absorb much energy and compresses to a certain degree thus giving less or zero percent noise.
Off-road wheels & noise factor
Typical off-road truck tyres boast large and rather knobby tread blocks that increase the point-contact pressure at ground. They easily dig into soft earth without dispersing the load or simply skimming over the surface that may even topple the vehicle entirely.
It’s however most unfortunate that on a smoother surface, these knobs treat the air in similar way; squeezing the air against the ground and compressing it. Large gaps in between the knobs further expand the air and this extreme cycle roars rather loudly and violently especially when driving at higher speed.
The low-noise treads
There’re two ways to condense tread noise;
- Reduce air compression or
- Cut-down the expansion factor
Truck tyre manufacturers often assemble wheels with solid treads all the way that effectively bear heavier load as compared to the open tread elements. Since no air gets underneath, the tyres are quieter.
Now that we know why tyres give a certain humming or roar, consider investing in a new pair rather only when the old wheels deteriorate completely.