* Worn wheel bearings: This is a very common cause. As wheel bearings wear, they can squeak, especially under load and at higher speeds. The squeak often changes pitch with speed.
* Brake components: While brake squeals are more common at lower speeds, worn brake pads, calipers, or rotors *can* produce a high-pitched squeak at higher speeds, especially if the wear is uneven.
* Tires: While less likely to squeak *only* above 40 mph, worn or improperly inflated tires can create noises that become more pronounced at higher speeds. Check for uneven wear or embedded objects.
* Drive shaft/CV joints: Problems with these components can produce a squeak or whine, often speed-dependent. CV joints (constant velocity joints) are particularly suspect if the squeak changes with turning.
* Belt tensioner/pulleys: While usually associated with squealing at idle or low speeds, a failing belt tensioner or pulley could produce a higher-pitched squeak at higher RPMs (speeds).
* Loose components: Something might be loose in the undercarriage, like a heat shield, that vibrates enough to squeak at higher speeds.
Troubleshooting:
It's difficult to diagnose the exact cause remotely. To pinpoint the problem, you should:
1. Check your tires: Inflate them to the recommended pressure and inspect for wear and embedded objects.
2. Listen carefully: Try to pinpoint where the squeak is coming from (front, rear, left, right). Does it change with turning? Does it change with braking?
3. Take it to a mechanic: A professional mechanic can perform a proper inspection to identify the source of the squeak and recommend the necessary repairs. Ignoring the problem could lead to more serious and costly damage.
Don't delay addressing this issue. A squeak could indicate a developing problem that could lead to a more serious failure, such as a bearing seizing, which could result in a loss of control.
