If you want to set specific width to each column, I believe that you need to specify the option tableLayout: 'fixed' . The docs refers to it like this:

tableLayout | auto or fixed | To make columns width algorithm auto or fixed

So your code could be something like this:

 const tableColumns = [

    { title: "Lorem ipsum", field: "lorem", width: "10%" }, // fixed column width

    { title: "Name", field: "name", width: "80%" },

    { title: "Custom status", field: "customStatus", width: "10%" }]





 <MaterialTable

    tableRef={tableRef}

    columns={tableColumns}

    data={tableData}

    onRowClick={(evt, selectedRow) =>

      setSelectedRow(selectedRow.tableData.id)

    }

    title="Remote Data Example"

    options={{

      rowStyle: rowData => ({

        backgroundColor:

          selectedRow === rowData.tableData.id ? "#EEE" : "#FFF"

      }),

      tableLayout: "fixed"

    }}

  />

Here is the sandbox.

Good luck!