Silly question fellas, I was curious is there a rule of thumb as to how wide the whites walls should be?
The ones on the rear of my truck where pretty wide..4 7/16". I honestly think there is not a standard but it depends on the era & style your going for. HRP
Also depends on the style of tire you're running e.g. HRP must be running cross ply Firestones in 7.50-16 size as they list the WW width for that tire at 4 1/2" and the 7.00-16 at 4" If you go to a similar size radial say 235/75-16 the tire is 2 1/2" smaller in diameter and only has a 3" WW but you should also know that radials are not "HAMB approved"
I'm not sure what you would call the era of the build but they would be going on crafts 15" 5 spokes. My car is a 37 Ford street rod.
To answer the question, if you want to build to a time period and depending on the car, yes, there are general rules. Up to early fifties cars, whites were very wide, then progressively got narrower. Early 60's real narrow, then 'piner' whites then redlines etc. Hot rods etc generally followed the factory trend. Wide whites on mags on a street rod has nothing to do with any period or traditional hot rod so really, please yourself.