I've got a 2005 Mazda 6 and lent my spare tire to a neighbor. Long story short the rim got bent and he replaced my spare tire. Upon inspection the spare tire he got me was a different size than the original spare. Is it ok to use the T125/70D16 spare tire on my mazda?
I found a spec for a 2009 Mazda6 where the micro-spare is listed as a T115/70D16 which has a 22.3" diameter. Your replacement 125/70/T16 has a 22.9" diameter. If your original was the same as the '09, a difference of .6" will be just fine for the limited distance you may need to use it.
