A half-ton truck is a consumer pick-up truck, not a commercial shipping vehicle. Much much smaller.

Yup that's what I had in mind, a 60s city delivery truck, not a semi, so googled that and came up to about 10t.

The Federal-Aid Highway Act of 1956 set the gross vehicle weight limit for trucks at 73,280lbs. I imagine trucks of the day probably at least came close to that limit?

https://en.wikipedia.org/wiki/History_of_the_trucking_indust...