BMW MINI – Did You Know? Tire Pressures Drop When Cold. Are Your Tires Unsafe?
Now that much of the nation is solidly getting into classic winter weather, the ambient temperatures are going to be running as much as 60 to 80 degrees colder (or more) than a few months ago. When was the last time you checked your BMW’s or MINI’s tire pressure? If your pressure was 32psi in mid August ….. what is it now? You may be driving on dangerously unsafe tires. Low tire pressure not only accelerates tire wear (click HERE for our article on tire wear and care), but becomes a major safety issue. Low tire pressure creates vehicle instability due to excessive sidewall flexing. This could turn a minor steering wheel correction into a major vehicle sway or skid, resulting in loss of vehicle control.
When your tires are filled with air (vs. Nitrogen), the pressure typically drops about 1 to 2 PSI for every 10-degrees drop in tire temperature. This may mean that your tires are under-inflated, if the last time you checked the pressure was in warmer temperatures.
NOTE: Always check your tire pressure with the tires “cold”. In other words, before driving, so that the tires are at the ambient temperature. As the tires are run, they warm up and this changes the pressure in the tire. If you set them at 32psi after a long summer drive, the cold pressure will be lower.
You checked your tire pressure in August and the ambient temperature was 85-degrees. You set the pressure to 32psi. You’re now into the winter months and the ambient temp is 15-degrees. If we take the average of 1.5psi drop for every 10-degrees drop, our tires would now be at about 22psi …….. quite under-inflated.
* When setting your average winter air pressures …. don’t forget to reset when the warm months come along!
Naturally, a good air pressure gauge is very handy to have in your vehicle. Here are some great analog and digital gauges to keep in your BMW/MINI …. or that other car.
Click on Image for tire pressure gauges: