R&T tested a standard MINI Cooper (no SS+) with
"Dunlop SP Winter Sport 175/65R-15 84T M+S" specification.
In the article, R&T stated the Dunlops were
"appropriate for rainy and snowy winter months, but they prevented the MINI from realizing its full performance potenital during our dry-weather track test". These Dunlops are specifcally blamed elsewhere in magazine for the MINI's poor skid pad showing of only .79G.
I've seen
Road & Track at WHSmiths in the UK, so I know it's available there.

Look for the yellow MINI on the cover.