[Roadsters] Datsun-roadsters Digest, Vol 2, Issue 357

[philip erickson]

If you drive any distance with mismatched rear tire diameters, you
risk permanent damage to the differential. So to be safe, a mini has
to still be the same diameter as the other tires you're using.

-- John
     John F Sandhoff   sandhoff at csus.edu   Sacramento, CA


Sorry John,
  But that is an OLD WIFE's TALE if you have an OPEN rear axle.
   
  50-100 miles would be not problem, and that's all you should be driving on a mini spare.