QUOTE(honkit @ Aug 23 2020, 01:16 AM)
My car only at 2000km. Alignment ok, balancing done.. It only vibrates at 100-120. After that ok..
Vibration at 100-120kmh is usually balancing issue. Doesn't Mazda 4S cover this complain since your car is practically brand new at 2000km?
If off wheel balancing doesn't help, they can do on wheel ridial force balancing or swap rear and front tyres. Tbh, some tyre shops sucks, they can even screw up simple tyre balancing jobs.
There's a lot of science in dynamic wheel balancing.
Some shops depend on untrain laborers to operate their machines, they will ignore the principles of balancing a wheel.
Watch them when they key in your wheel diameter, width, and offset into the computerized balancing machine, if the operator did not enter the correct parameters you may not get perfectly balanced wheels.
Do they know how to match the yellow dot which is the lowest weight of tyre to highest weight of wheel, the valve stem?
Or do they match the red dot of tyre which is the high point for radial force variation to the dot for low point on the wheel?
Another reason could be due to a tyre which is out of round. Get the service center to check the tyres for defects, there are certain procedures that they can do to identify a tyre quality issue, make sure they do a thorough job.