Semiannual values of the dynamic pressure and the static pressure in the solar wind are calculated for 1965--1988. Using the statistical relationship between the tail lobe magnetic field and solar wind parameters, variations of the magnetic field pressure in the magnetic lobe at X=-20 RE are predicted. This prediction is compared with various satellite observations of the total pressure, although systematic observations were not available on a continuous basis. It is predicted that the semiannual value of the magnetotail total pressure exhibits the variation with a period of ≈11 years in close conjunction with the solar cycles. The magnetotail total pressure tends to be minimum at the maximum epoch of the sunspot number. ¿ American Geophysical Union 1994