Tires: Bulges in tires, rubber manufacturers association, rubber dust

Question
I am an entry level technician at a big dealership in New England. a few days ago i received an RO for a flat tire. the flat was in the trunk and a donut was on the vehicle. now i inspected the tire to determine what caused the flat and found a small hole, which looked like it may have been caused by a large nail or screw that had fallen out prior to my services. also the low tire pressure and the customer driving it caused the tire to come off the inner bead. I then set the bead and inflate the tire as much as possible with the hole.  I plugged the tire, then set the tire pressure to factory spec(around 32 psi). After performing the service and during, I noticed no other damages, to the tire or rim. I then shipped the car. The next day at work i found out, the customer only got 1 mile down the road and felt vibrations.  The vehicle came back and there were several bulges in the inner sidewall. Needless to say I got in trouble at work for not noticing the bulges and sending a customer home like that.  i plead that i didn't notice the bulges before hand, but they wouldn't have it.  Is there anyway that the bulges could of revealed themselves after the vehicle left the shop? i appreciate the time.

Answer
Bill,

The first thing you need to do is find the Rubber Manufacturers Association web site (www.RMA.org) and read about repairing tires.  A plug is not acceptable, plus you are supposed to inspect the tire inside and out before doing the repair.  Had you inspected the tire inside you probably would have found rubber dust - a sure sign of run flat - and not performed the repair.  (The clue for me was the dislodged bead.)

Never repair a tire that shows any signs of runflat or extended underinflation.  Those signs are rubber dust inside, discoloration of the tire (usually it's a bluish cast, but sometimes it's a "more black" look, and it can appear on the inside or out), sidewall cracking especially the lower sidewall, abrasion inside or out, blisters inside, etc.  When you find this - THE TIRE MUST BE REPLACED!!!

In other words, the inside has to be absolutely pertfect.!!!

BTW, many of the new "RunFlat" tires - the ones where you can travel up to 50 miles after the puncture - are not repairable, because you can't see any signs of damage even after 50 miles.