what tyres for my series 3 SWB

hi there everybody. i just bought myself a swb series 3. everything is tip top except the tyres are almost bald. at the moment i have some 205 r16 but i cant tell you the height of the profile as it is not written on the tyre. my question is this. what is the minimum and maximum width and height of tyre that my landy can use without any problems?thank you for your time and look forward to a reply.

I have a set of 4 colway mud terrains on rims about half worn they are 235s and will fit straight on if you interested!??
Graham