What is the front and rear wheel load of a fully loaded concrete truck?

That'll be dependent on the configuration and state laws. United States Federal DOT regulations allow for a total of 34,000 lbs on tandem drive axles, and the front steer axle may have up to 20,000 lbs. so long as the vehicle doesn't go over the allowed weight rating.

State law may allow for heavier weight ratings on secondary roads, but usually not on federally maintained Interstate highways unless the state was granted a grandfather clause for their permissible weight rating when the federal DOT regulations were established.

For information pertaining specifically to your state, you would be best advised to contact your state's Department of Motor Vehicles or motor carrier enforcement agency (which will usually be some division of the State Police in US states, the MTO in Ontario, or a division of the RCMP in the remainder of Canada).