I recently purchased 6 7.00-18 for my 1946 3800 dually. It was expensive at about $1300 for tires, freight and installation, but worth it to me. There are not many options these days for that size tire (I bought the Super Transports) and I don't know about the 5 or 15 degree lip, but so far so good for me.

1946 Chevrolet 3800 1-Ton

In the Stovebolt Gallery
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I understand computers and I like them, just not in cars.