[justjim]

Originally Posted by PaulDenise

If you have steel wheels, then one possibility IMHO...

The holes in the steel wheels are a little larger than the studs that they attach to. When the wheels are put on at the factory, the wheels 'slump' down just a little because the cart is up on a lift and the wheels dangle down. Then the air gun runs the nuts on. When this happens the little cone shape that is pressed into the wheels at manufacture to center the nuts is distorted and flattened on one side.

So what happens when you drive it, the wheel is actually off center by an eighth of an inch. It feels like you have a tire that is flat in one spot.

To check this, pull off a couple of wheels and look at the wheel and see if the cone indentation is still correct. Or, you could jack up the front and just spin the wheel and with a finger see if it is not centered. Can't do that on the rears.

If you replace the tires carefully, you can get them on properly, but the malformation will always be there. So, if you find it, you might take it back and ask for new wheels.

What you post makes sense to me. I know “cold” will cause the tires to thump until warmed up but that goes away after a mile or two.