A Guy asked me today..."what is the min. distance from the tire to spring"? I told him...no closer than 1/2"...any other opinions?
I would feel comfortable with 1/4" unless I was auto crossing. I wish I had that much to the fender though
I'd say 1/2" is pretty safe as a general rule but just too many variables to really nail a specific number down. Fatter old school 60 or 70 series sidewalls(even bias plys?), tire inflation psi, leaf spring stiffness, bushing types and current condition, lowering blocks, type of driving, etc, etc.
Mine is 1" and I am running 255 60R 15 But I would be good with anything over 1/4" like Yellow said as long as you weren't flexing the sidewall into the spring