Originally Posted by Victor Benz
I agree completely with almost everything you've listed; however I have not heard the bit about having an under-inflated spare before. Its a given that it needs to be fully inflated upon installation. What is the rationale for this?
To me, its the same as the advice to take the pressure off the main (mounted) tires
as recommended by a number of manufactures such as Goodyear (bullet point #4)
But I should add that this recommendation does not seem to be universal and I am open to debate on the question.
I have heard the the higher pressure on the inside causes more rapid oxidation on the inside than if they tires
were, for example, unmounted. That however might just be snake oil.
EDIT: Another valid point is that when you have a flat and need to use the spare, you might be in a place where you do not want to wait on your inflator to does its job. So in that case, a fully inflated and ready to go spare would be better.
Also, on the question of just buying new tires
already mounted, I would only do that if I could get them with metal valve stems.