Wheel and Tyre Sizes

[kevinday]

Can anybody tell me if there is a rule to calculate minimum/maximum tyre width for a wheel width? For example if I had a 6 inch wide wheel what is the minimum and maximum tyre widths that can safely be fitted? Is it a percentage, or, plus 30mm etc.?

[CleG]

M@t's your man .. he will deff know that calculation