A spare tire is needed like a snooze button on a smoke alarm. If you dont stray more than 40 miles in your dd'ing, its a waste of weight, space and everything else. How often does somebody tear a tire to the point of not being able to drive it to a shop? Even if you get a nail, pressure wont drop almost always until you pull it. The only situation I can recommend a spare for is long distance trips.
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2 x N54 -> 1 x N55 -> 1 x S55-> 1 x B58
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