Pretty sure you’ve all heard a good bit about Deflate-gate by now. You know, those 11 footballs that were somewhat deflated in the Patriots win over the Colts. We’ve watched the physicists, players, coaches and analysts debate, and we still have no idea what actually happened to those footballs, but we do know that you should keep an eye on the deflate-gate going on in your driveway this winter.
Did you know that tire pressure changes with the temperature? For every 10 degree Fahrenheit change in air temperature, the air pressure in your tires will change by about 2% or 1 pound/square inch (it will rise in heat and lower in cold). It’s gotten pretty cold out there, especially for our friends in the northern states, and we bet they’ve seen some deflation happening in their own tires.
It’s not unusual to go get in your car on a very cold morning and see that flashy tire pressure light on your dash. Tire pressure monitoring systems are great things, and no one can deny their usefulness in keeping us safer on the road and helping to prolong the life of our tires; but no one wants to see that light on first thing on a 10 degree morning. No one. Ever. That’s science, though. The air you generally fill your tires with is about 78% nitrogen, 21% oxygen and the rest is water vapor, CO2 and other gases. Gases tend to expand and contract with temperature changes (increase in temp means expansion, and a decrease causes contraction); water vapor also has this tendency. One way to combat that pressure change is to have your tires filled with pure nitrogen. Pure nitrogen lacks water vapor and tends not to expand and contract as easily as oxygen with temperature changes; couple that with the fact that oxygen is more likely to migrate through the rubber of your tires than nitrogen, and nitrogen fill seems like a no-brainer. We fill tires with nitrogen more and more here at RNR because keeping tire pressure at the correct level and as constant as possible will help to extend the life of your tires (and you’ll have to check the pressure less often–one more thing off your to-do list!). If you live in a city where an RNR store is located, you can get nitrogen replacement for just $20–not bad for achieving 25% longer tire wear. Tires are a big investment, and nitrogen fill can go a long way in prolonging the life of your tires (and keeping you out of the freezing cold on those early mornings).
Just a little warning, if you don’t want to get out of your car in an arctic burst of air, and you decide you’d rather drive around on low tires, you should know that your TPMS (Tire Pressure Monitoring System) doesn’t alert you to a pressure problem until your tires are 25% lower than they should be. Driving on under-inflated tires can cause uneven wear and can cause your tires to overheat (because of the extra friction created when more rubber meets the road). Overheating can cause tires to separate or blow (though, arguably, this is a more common occurrence in summer temperatures). If you’re considering nitrogen fill, you should know that nitrogen runs cooler than “regular” air, as well.
We can’t answer the many questions surrounding those deflated footballs, but we can tell you that deflation happens. It’s not all road hazards and blow outs, either. Temperature change is definitely something to keep your eye on, especially if you’ve chosen not to switch to nitrogen-filled tires. So, stay safe on the roads this winter–check your tire pressure!