[Rod in Smiths Falls,]

The roads are all asphalt in pretty good condition.

The more I think about it the more likely the rims seem the culprit. One rear is bent a bit, though on my 4Runner a similar out-of-allignment rim has caused no problems. On a smooth highway at 60 mph this afternoon I could see the box vibrating in time with the thumping of a back wheel.

I think the alloy rims came on the truck when purchased new. They have a Toyota logo on them, at least. I looked through the purchase documents which were included with the owner's manual and couldn't find any reference to the option list, though.

If the rims were a bit loose on the wheels, they'd act just about the way they are doing.

How would a bent axle behave?