I have a strange issue with my left rear tire. It is a Good Year Integrity tire 185/65/15 with 50% thread left. I inflate it to 40 psi. It started to shake at exactly 63 mph. Went to walmart and those guys said they can not balance it. The machine just asking for more and more weight at different places and it does not make any sense to them. Since I mostly drive local (100 miles/day) at 45 mph max speed, I am not really in a hurry to solve this problem. I am more interested to learn what's the real problem. Today I had to go on free way for a while, and I did not even notice that I was at 70 mph with no shaking for a mile or so. Then I lowered speed to 55, but when I speed up again, it starts to shake at 60 up to 67 (I did not go higher). At 58 mph it is perfect. All of this time the road condition are consistent, typical condition of most free ways. I am thinking about putting two winter tires on front during the winter season. Is that a good idea? I am in Chicago.
In my opinion this is caused by debris inside the tyre possibly due to structural damage within it's construction. Having the tyre removed from the rim and inspected would confirm or deny this, but ignoring it is asking for trouble. The wheel bearings are being subjected to a continuous vibration loading as are the suspension components, that will not do them any good. Fitting two winter tyres on the front to give traction is generally considered on PC a bad idea leading to problems of over steer. John (Britprius)
Perhaps there is some damage to the tire which results in something being loose within, hence the balance machine is not able to balance the tire. I would suggest that you get rid of that tire. It is not considered good practice to use only two winter tires as the car will oversteer which means the rear end will slide around.
Like above, sometimes water in the tire from excessive lubricant use upon mounting and/or a compressor that is not drained regularly can cause shifting imbalance. Also, some types of fix a flat maintain a substantial liquid presence within the tire with the same results, shifting imbalance as measured on a balancer.
All, Problem solved. I put too much "Fix it flat" into the tire (not the canned ones, but the greenish stuff sold in Walmart). I found 1/2 qt of them in the tire. Now it is replaced.
