Wheels / Tires: 1947 champion

[ma1951]

The 1947 champion book and tire vendors lists to run 550-15 tires. The 1949 champion lists to run 640-15. I thought they were pretty well the same car. Does anybody know what the difference was about running the difference size tires and is anybody running the larger size on their 1947 champion?

[unclemiltie]

They changed the numbering used in 1964 and then in early seventies they went to numbers and letters. I use to run 735 which is wider on my 47 for years. I thought they gave a better ride

[Greenstude]

I am presently using 195R75-15 radials on my 1947 Champion. They must be very close to the correct size, as my odometer error, when compared to a GPS, is 0.7 miles in 100 miles.