If you go to Grigg's Tech Article on wheels and look at the charts from the 1949 Budd catalog you'll see a Firestone design that is named the "RH". Yours should be similar, or maybe an older design called an "RI". They have continuous/non-split rings. If you have split rings they are probably Goodyear "L" or "LB". You should be able to find the rim/ring design stamped on them if they aren't too rusted. Whatever you do, don't mix-match the rim and ring sets. Very dangerous to mix-match because the components are made to work together. They can come apart violently if mix-matched. Stu