Originally Posted by retiredguy
... If you have a flat with a run flat tire do you have to replace one or 2 tires. Believe in Ontario that both tires have to match, but I am a real novice re tires. Thanks again.
As long as you can get a tire of the same brand and model (and obviously the same size) there is no need to replace the other side tire. If you can't get the same brand/model, it's a good idea to check the specific tire specifications. Tires of the same size made by different manufacturers can vary a little in rolling diameter (number of revolutions per mile)
If the difference is small (less then 1%) it's probably OK to mix brands (but not recommended). If it's more, you may have problems with the stability control system sensing an error. Also, it's never a good idea to have tires with different traction characteristics on the same axle.