between 35 mph to 45 mph, i get a rumble type noise, like driving over road about to be paved. Once over 45 car runs smooth. Tires have been balanced and rotated twice. Steering is firm and steady other wise.
My car has 75000 miles.
My car has an automatic transmission.
An unbalanced driveshaft is a possibility as is a faulty torque converter. Tires cannot be eliminated without much further testing including testing on a road force variation balancer. Even perfectly balanced tires can create terrible vibration due to the construction (particularly stiffness) of the tire sidewalls. In addition, perfectly balanced tires can have internal tread defects that will cause vibration. Chassis ears and/or a frequency analyzer (that decomposes the frequency of noise which allows assignation to "likely" types of origins) might be necessary to resolve your issue. If you request a vehicle vibration diagnostic, the responding certified mechanic will get this resolved. If you have further questions or concerns, please do not hesitate to re-contact YourMechanic as we are always here to help you, particularly if you just need more information to make a wise, informed decision.
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