This catalog confirms my long standing belief that the hubcaps were the first change on the wheels which are still metal here in the catalog photos. Even the 26ers are sporting metal wheels with plastic hubcaps and the classic straight line rubber treads. Now one thing to keep in mind is that 1971 is the last year that the wheels are described as "white wall rubber tired wheels". Beginning in 1972, that line is omitted. Though the '72 catalog features the plastic rims with rubber treads which may have occurred in or during '71. As kettle colors did not change from the previous year these could be 1970 models pictured. These are the kind of details that keep me up late at night trying to pinpoint. Though I'm proud of how much more we know now about 1970-78 kettles than we did just three years ago. Also note that the kettles are still marked as PAT PENDING in the corners of each picture. Patent was granted on 11/10/1970. That continued into the 1972 catalog.