Interesting... Those are Firestone RH5° wheels, and rightfully so nobody will work on them. You should try to replace them with a safer wheel design, which at this point is any other kind of wheel.

Some useful info and reading about different wheel types in the beginning of this tech tip, and Cross section pictures of the wheels.

http://www.stovebolt.com/techtips/wheels/

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-