I found the following measurements at http://www.ringgear.co.nz/Our_Products.shtml#MG. The difference is in the last number, which is labeled "Ref." It can't be mm, because it comes out too large. What does Ref. mean?
MIDGET
MK 11 1098
1300 104 265 236 395
446 [MRS 05]
MIDGET
1966-73
MK 3/4
SALOON
1100 MK1
1275CC
INLINE 104 265 236 446 [MGS 68]