6.50 or 7.00 will look OK on your truck. 8.25 will be much too big and ugly. I have 6.50s on my 1936 1-1/2 ton. They look good. It had 7.00s when I got it and they looked too big to suit me. The offset in your wheels will determine how big your rears can be.
Even with the similarities between '36 and '37, I think your '37 can take a larger tire and look OK.
You can see some pics of my truck on Jim Carters site. It was feature truck for November 2016 (I think)

Mike

This might get you there http://www.oldchevytrucks.com/blog/index.php/2016/11/1936-chevrolet-1-12-ton/

Last edited by 35mike; 10/22/2017 2:59 AM. Reason: added info
1936 1-1/2 Ton (RD) Stake Body Original
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