Tires: Tire repair, quandrant, tire repairs

Question
Hi Barry,  I am a firefighter and my wife stopped by tonight to say hi.  The left front tire was going flat on her car and I found a nail in the middle of the tire.  She went to firestone for the repair and they found a second nail in the tire and told her that they could not repair the tire because the nails were less that 16" apart.  I have never heard of such rule about a tire being unsafe if the nails are less that 16" apart. Well they sold her a new tire. Did we get taken for a ride? Could the tire have been fixed.  The 2 nails were small and in the middle of the tire more than 8" apart because I did not see the second one and the nails were not in the side wall. Thanks.

Answer
Tom,

There are 3 things to consider about repairs in tires:

1)  The repair must hold air as well as the original.  That means a patch.

2)  The repair must seal the hole both from the inside and the outside to prevent water from getting to the steel belt.  That means a plug.

3)  The repair must "bridge" the structural damage - and even a hole causes stresses to concentrate.  So that means a reinforced patch.

The only approved method for repairing tires involves a plug / patch combination.

And since distance between repairs affects the structural integrity, it is common for many repair shops to refuse to do a second repair within the same quandrant.

But it isn't like there are hard and fast rules about this.

Plus the biggest problem regarding tire repairs is the fact that the tire was underinflated for some period of time - and I'll bet that's why the tire shop refused to do the repair - because it is easier to explain 2 holes, rather than the damage done due to underinflation - which you can't actually see.