Tallest/widest tired on 14x5.5 rim for 74 Scamp?

[74RR]

What the tallest and widest tire I can fit on my 74 Scampwith a 14 x 5.5 rim? Any pics?

 

[74DartSwinger360]

Rear 235-70-R15 with a 4.25 backspace
With HD Springs

As for rim width i dont think it matters my dad runs 275-60-R15 on a 15x6 factory rallye on his 68 Charger R/T.