I have run flat tires on now, but before winter I hope to replace them with regular tires, is there a better size to go with than the 205-55-17 that it came with? Also if I get a mini spare rim are the bolt patterns mini cooper specific.

 

You can also consider 225/50-17 non runflat Grand Touring All Season tires. These will fit but do cost more depending on model. Some will work well with wet weather or light snow.

You don't really need to stick with a summer tire, grand Touring is for daily driving and street use with more comfort and longer treadlife. All season means you can drive it in cold temperatures under 40 degrees.

Spare rim will fit standard MINI bolt pattern if you search tirerack for wheel replacements for the Countryman. Cooper is same as other models.