Truck scales tend to be not accurate at low weights, been there done that
I bought a pair of used CA certified 1000 Lb. warehouse scales that my old company had before I retired and moved up to Bend, I made a set of wooden platforms that are the same height as the scale tops and I now use them to scale my cars
Oregon has truck scales all over the state, they don't man them 24/7 and you can drive onto the scale and see the weight on a digital display on a pole outside the shack, my old pump gas Duster showed to be 200 lbs. heavier on them than on the certified race scales at Las Vegas drag strip 3 weeks later