I know many of you have seen this video but I want you to look at and pause it at the paoint where you get the best view of the wheels on this thing. What size tires do you believe those would be on a real Mini? They look like a set of 17x8 or 9 with some 265's on it.
http://www.zippyvideos.com/18151104322005.html
I'm actually thinking about building my Mini to look like this one. Except the colors..:smile:

 

Nice video of an RC classic mini with larger wheel arches.
To make it look similar and do it on a classic mini would be difficult.
The wheel arches are much more limited than with our new MINIs.
265mm probably is way too wide unless you got a custom built rim with a really deep lip. Clearance inside the wheel well would be the problem and alot of the wheel would have to hang outside the fender. larger fenders are required for a finished look.

17" looks about right on diameter but you'd have to check what is the largest outer tire diameter that will still fit a classic mini.
From
http://www.caranddriver.com/article....&page_number=1
The tires used were 175/60-13 so tire diameter was 21.1" and the wheels look like they fill the wheel wells adequately.

For tires as small as 205/40-17 the tire diameter of 23.4" would be large for the classic mini. When looking at tires even wider the outer tire diameter gets larger and larger which isn't practical unless you changed the suspension in the rear to allow for that. At 245/35-17 outer diameter is 23.8" and fits rims 8 to 9.5" wide. That's probably your limit on wide tires with as small an outer tire diameter as possible.

At 255/40-17 you'd need a rim 8.5 to 10" wide, outer tire diameter is 25" which is pretty big. A wide tire and rim like this would be really heavy and not a good match for a light weight classic mini.