Maximum tire width for a 56 Chevy

I am wanting to know how wide a tire can be fitted in the rear of a 56 Chevy car with stock springs and no mods to the fenders.

Thanks in advance!!

 

http://www.trifive.com/forums/showthread.php?t=2090

 

I've put 9.00x15s on them with a hat trick. They were on Chrome reverse and I don't know what can be done for sure with a different wheel setup.

 

Check trifive.com forum, they have beat that topic to death and have a calculator for both front and rear tire/wheel size that is accurate. Regards, Steve