A Puzzling Shake in the Front End

pontiac
g5

#1

I commute 50 miles one way. On my ride home from work, about 20 minutes after I leave. I notice a shake in the steering wheel that is visibly noticable. If I happen to touch my brakes, the shake becomes violent and lessens when I step off the brake again. After about 5 miles, it goes away completely. Here is the puzzling part. This ONLY happens on my ride home, at the same point in my commute, which starts with a slow down hill followed by a long uphill. It does not happen any other time in my drive home, or at all to my drive to work.



I am due for tires soon, although there is no abnormal wear at all.



I have taken the car to a mechanic, who has told me I need two new front tires, and that should fix the problem. He did not tell me if they were worn weird or anything. He looked at the car up in the air, and did not see anything loose or broken at all in the suspension and brakes.



So can anyone point me toward a possible problem? I don’t believe it is solely a tire problem, that doesn’t explain why it only happens 1 time in my commute. Also, I have yet to feel this vibration in the wheel any other time I drive my car, no matter the distance.


#2

Could it be the road?


#3

Switch the tires front to back and see if it makes any difference.

If you decide to buy two new tires they should always be mounted on the REAR axle, not the front.


#4

It could be a ballance problem that starts when you hit a bump or washboard surface on the road. The fact it gets worse when you hit the brakes, suggests it could be a loose bearing/axel nut. another possibility is that you have tread seperation, and the tires start to squirm once they get heated up, but I would expect that to happen every time you went a certain distance.