The heat of summer can do a lot of crazy things. It can fry an egg on the sidewalk. It can cause your skin to breakout. Oh, and the heat can make your tires explode.
Yep, you read that right. When temperatures soar during the summer you’re more likely to have a tire blowout. Here’s why.
Science Lesson: Why Heat Causes Tires to Expand
Tire air pressure increases as the temperature goes up. Scientists have figured out that for every 10 degrees (Fahrenheit) that the temperature rises the tire pressure will increase by one pound per square inch (PSI). Doesn’t sound like much but there’s typically only 30-35 PSI in the tires of passenger vehicles.
A few pounds of air pressure can make a big difference. Such a big difference it can cause a tire to pop. Even if it doesn’t give out, over-inflation can cause a tire to prematurely wear and interfere with braking.
There are three things at work:
Hot Molecules - All materials are made up of atoms and molecules. When molecules get hot they start to vibrate intensely. The vibration causes expansion. Being that there are molecules in the air, now it’s easy to understand why air-filled tires expand in the summer.
Friction - As you drive down the road your tires are rubbing against the asphalt. This generates a fair amount of friction, and friction creates heat that makes your tires even hotter.
Rubber - The third part of the trifecta is what tires are made of - rubber. Rubber molecules are linked together in long, twisting chains (polymers). When the polymers vibrate they contract rather than expanding. Tire rubber is made so that the polymers can’t coil in on themselves, but everything has a breaking point. Think about a rubber balloon. If you keep blowing air into it eventually it’s going to burst. The same thing can happen to a tire.
What to Watch Out For to Avoid a Blowout
Are you on the brink of a blowout? Here are signs you need to pull over and let your tires cool down.
Tires that are hot to the touch - The most obvious sign that your tires are overheating is how they feel.
Excessive air pressure - A tire pressure gauge will tell you if your tires are overinflated.
Don’t rely on the tire pressure monitoring system (TPMS) - Many newer vehicles have a TPMS that sends an alert when the tire pressure is too low, but your system won’t warn you if the pressure is too high.
What to Do to Prevent a Heat-Related Tire Blowout
Safe driving starts with taking a state-approved drivers ed course, understanding the rules of the road and maintaining your vehicle. There’s nothing you can do about the heat, but there are steps you can take to avoid a tire blowout during your next summer drive.
Keep your tires properly inflated - Safe road driving requires that tires have a certain amount of air pressure. What’s consider the proper amount of air pressure varies depending on the car you drive. Go with the vehicle manufacturer recommendation, which should be noted on the inside of the driver door and owner’s manual. Be careful not to confuse the “recommended” amount with the “maximum” amount listed on the tire itself.
Keep an eye on the air pressure in the tires - Measure the air pressure with a gauge before you begin driving. Check it again every two hours or 100 miles.
Don’t drive until your tires cool down - You might think the best thing to do is let a little air out the tires so you can keep traveling down the road. Wrong! If you let air out you run the risk of driving on tires that under inflated, which is equally dangerous. The best thing to do is wait it out until the tires cool off.
Replace worn tires - If your tires are already worn thin they’re more prone to a blowout. Consider getting “summer tires” that are designed to handle better in high temperatures.
Clean and treat wheels - Treating your tires with a wax-based product can keep them from drying out.
Stay Within the Speed Limit - The slower you go the less friction there will be. Less friction means less heat.
Pay attention to the load weight - The more loaded your vehicle is the more weight there will be on the tires, increasing the likelihood of a blowout.