I normally drive an International P700. The thing shimmies between 55 & 65 MPH. I sometimes feel that it is going to shake apart on the highway. It's so bad that the passenger door will shake open as I drive down the interstate. I told my mechanic and he said that there's nothing he can do about it. He said that UPS is buying poorly made recaps and that I am not the only one complaining. I asked a few drivers and they had the same story. I mentioned it to the shop supervisor and he told me to drive below 55 MPH. This might have contributed a little to my 47 lb weight loss, but enough is enough.