what objects did I see under a dump truck's wheels?

I was driving to work today, and a cop’s SUV was pulled over behind a dump truck.

The dump truck was a 10-wheeler, with double-wheels on the back, so 6 outside tires, total.

Right in front of each of the six outside wheels was an object. It was basically a metal plate, about 24 inches long, and 10 inches wide. It was flat for most of its length, and then the last 10 inches, was a “box”. It was about 3 inches high, and extended from side to side.

These weren’t chucks, placed to stop the truck from rolling. The objects were laid to the side, with the raised box outside the line of the tires. If the truck rolled forward, it just would have rolled over the plate part, and the plates were probably only 1/4" thick. Also, they had a shinier disk on the top of the box.

Any idea what these were? This was on the side of I-95.

Hmmm.
The cop was using scales to make sure the garbage man wasn’t too full of trash.

my guess would be a truck axle scale to measure the weight of the trailer to see if it was overloaded. (trucks that are too heavy can damage the roadway.)

I was thinking they were some kind of scale.

They didn’t appear to have gauges on them though.

They looked quite distinct from sotmething like this

http://images.google.com/imgres?imgurl=http://www.sperlescales.com/images/Truck_scale.jpg&imgrefurl=http://www.sperlescales.com/MSI%2520Load%2520Ranger%2520Wheel%2520Pads.htm&h=304&w=375&sz=19&hl=en&start=18&sig2=TSvLu0dwXZ8ufEjB50mZmw&um=1&tbnid=IYi9f3NmCD7krM:&tbnh=99&tbnw=122&ei=F8gDR5X6EKe6gALO6cn2Cw&prev=/images%3Fq%3Dtruck%2Bscale%26svnum%3D10%26um%3D1%26hl%3Den%26safe%3Doff%26sa%3DG