Your right I meant to say Larger molecule (my bad). Any way here is a clip from one of our service bulletins at work From GM who as I stated earlier neither recommends or discourages nitrogen use in tires.
Nitrogen use in on road vehicle tires.
A common explanation: “The larger-sized molecules of this gas compared to atmospheric air means less slow leaks caused by air bleeding out of porous alloy rims.” Nitrogen makes up 78 per cent of the air we breathe, so 100 per cent nitrogen isn’t likely to have much effect in holding tire pressure on old and corroded wheels as suggested within the industry.
It is perceived that it will let tires run cooler, which is why race cars and airplanes use nitrogen.” It’s highly unlikely that a minivan or SUV will have its tires subjected to the extremes that track cars and jets experience, so like less air leaks, this benefit is highly doubtful.
The only benefit of using nitrogen is less pressure variation with temperature changes. Repair shop air compressors, air-lines and air-powered wheel tools are subjected to a lot of moisture contamination. Even the best shops that drain the water from their compressors daily and use water traps on every bay’s air-line can have high water content in their compressed air. When they fill tires, this water goes in with the air, causing increase in air pressure when the tires warm up; the moisture droplets expand, increasing the pressure. When temperatures drop the moisture droplets contract, decreasing pressure. Nitrogen is compressed for transport and shop use under processes that ensure low water content resulting in more consistent pressures.