Ethical Litmus Test: Ask service stations if they recommend nitrogen

A few weeks ago, I read in the Pioneer Press car advice column that nitrogen was better to fill your tires with because the pressure wouldn't vary as much with temperature. Since I had been thinking about what a "slop factor" temperature-based variation does create in maintaining optimal tire pressure, my first reaction was "wow, that would be great, although it just turned something that was free (air) into another consumable to be nickel-and-dimed by.

Then as I thought about it over the next day or so, I began to smell a rat. PV = nRT, the ideal gas law, hasn't been repealed, right? So I did a little quick web research. I found a couple of sites that tried to explain it was due to the larger size of the nitrogen molecules. But that, too, was quickly debunked. Basically, for applications other than race cars, the effect is undetectable.

As a postscipt, it occurred to me that this question could be a great, shorthand ethcial litmus test for assessing a candidate service station. Ask them "do you recommend filling tires with nitrogen"? If they respond "yes", cross them off your list.