Question:
I just got a new Grand Prix; the ride feels like the
tires wobble. I took it back three times. They adjusted
the tire balance, replaced two tires, put 27 PSI in
the tires, and then put 29 PSI in the tires. On the
doorjamb it says 30 PSI. On the tire it says 44 PSI.
What PSI should I use, and do you have a suggestion
for a smooth ride? I have a new car; I would like a
new ride.
Answer:
I’m sorry that you're having trouble with your new
car. I can imagine how frustrating it must be. I
would suggest inflating the tires to the specifications
on the doorjamb, not what it says on the tires. The
specification on the tires is the maximum inflation
for that tire on any car, but the information on
the doorjamb is the correct inflation for your specific
car. So go with the 30 PSI on the doorjamb.
Next, if you're still having the wobble/vibration problem
then they haven't yet found the cause. I would ask
them to do a road force balance on each tire and wheel
assembly and show you the printed results. A road force
balance is more accurate because it simulates the force
of the car on the road rather than simply balancing
the tire with no load. If they don’t have the equipment
to do this, find someone who does. That will eliminate
the possibility of a tire or wheel problem.
If the condition is still present, the brake rotors
and/or drums need to be checked against specifications
for lateral run out. Finally, the wheel bearings should
be checked for defects. I’m betting it’s a tire/wheel
problem. Sometimes brand new cars have been sitting
on the dealer’s lot for an extended period of time.
That can cause tire problems.
The final thing you might have to do is this: ask the
dealer’s service manager to go for a ride with you
in your new car, and then a ride in another new car
of the same make and model. If there is a difference
in the ride between the two, then the service manager
will know that there is still work to be done. If the
two ride the same, then maybe it’s not a defect, but
a characteristic of that make and model.
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