Dear Tom and Ray:

Upon leaving my house one day last week, I noticed my car had a flat tire. It is virtually impossible to remove a wheel previously installed with an air-operated impact wrench, so I chose to use a can of "Patch a Flat" and immediately drove to a local service station to have the tire plugged. I was informed that the repair would cost $20.00 due to the fact that the tire was full of butane which could explode, requiring the tire to be flushed out with air before being removed from the rim. My question is: Is the above true, or is that just a tricky way to justify a $20.00 charge?
Glenn

RAY: It's not tricky at all, Glenn. Here's the story.

TOM: Until a few years ago, most manufacturers of these "flat- fix in a cans" used potentially flammable hydrocarbons like butane as one of their ingredients. And there were instances in which sparks were generated during tire removal, and mechanics were seriously injured by tires that exploded.

RAY: A couple of years ago, after a spate of bad publicity (and a few humongous law suits), the flat fixing products replaced the explosive hydrocarbons with non-flammable ingredients. The manufacturers now claim these products are entirely safe. But your mechanic was using extra caution, because he had no way of knowing what brand you used, whether you just bought the stuff yesterday, or whether it's the flammable kind and has been sitting in your trunk for the last five years.

TOM: So rather than taking a chance on blowing his lips off, he decided to fill the tire with air and deflate it several times to flush out any flammable substances. And I don't blame him for taking extra precautions. In fact, 20 bucks for that kind of risk is quite reasonable. I would have charged $300!