Individual wheel weight scales.

Dana67Dart said

You really only need 1 scale. Weigh each wheel seperately. The combination the 4 weights will be the total weight of the car.

With the correct cantileivers you could even use a bathroom scale. (Dimensions are for example, but would work)
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I did that too. I had access to an industrial beam scale that could weigh up to 1000 lbs, so I built three platforms the same height as the scale for the other three wheels.
Trouble is, I don't have access to the scale any more, the company I worked for folded, and I retired.