Hey Jerry,
Don't know if '54 and '47 are exactly the same; but, Chevy's restoration guide for the '47 AD gives 56 9/16 for the front with 6.50-16-6 ply and 57 11/16 for 15" 6 ply. It says the rear widths are 69 3/4 and 70 3/4 respectively. Hope this helps.
Regards,