How does air temperature impact vehicle tires?

Getting in your car in the wintertime can be a miserable experience. Your engine takes longer to warm up before the heater starts to kick in, and meanwhile, you still need to scrape the frost away. Nothing seems to perform quite as it should, and that layer of ice and slush prevents you from enjoying your car the way you want to.

With so much going on, the TPMS light glaring at you on the dash is likely not a chief concern, tire pressure changes with the air temperature. We’re here to explain why air temperature matters and provide some pointers on how you can maintain steady tire pressures all year long.

Why does air temperature impact tires?

Remember when you were falling into a daze in science class? Even though the professor seemed rather enthusiastic about the lesson, all you could do was ponder how that information would actually pertain to you in real life. Well, the relationship between gases and temperature is something that will help you understand why tire pressure changes.

As temperature increases, gases expand, and they contract as it decreases. How does this relate to tires? On a hot day, the air in your tires takes up more volume than it will on a cold day. Increased heat means increased air pressure, while the opposite is true for the cold. Think back to the first cold day in the Fall, or even late Summer. Your TPMS light probably came on because the drastic change from hot to cold caused the air in your tires to contract.

Is air pressure all that is impacted?

Air pressure is impacted significantly by changes in temperature. However, it may not be the only area of the tire that could experience issues. If you run different tires to match the season, you might notice that the tire fails to perform as well as it should as the seasons change from what the tire is intended to handle.

For example, winter tires may have traction (or worse, blowout) issues during the warmer part of the year, while summer tires struggle to grip the road in the cold. This is because the compounds are designed to provide optimal performance in designated temperature ranges.

Fortunately, most drivers use [all-season tires][1] these days, so temperatures would have to be relatively extreme to hurt their performance. For those drivers who still need to use [summer][2] or [winter tires][3] due to their vehicle type ([sports][4] and [performance-oriented][5] cars) or location (areas that get a lot of snow and ice), paying attention to the fluctuating temperatures and weather forecast is a must as the seasons change.

Is this a concern in all areas?

It’s important to understand that all of this information is relative. How much of an impact temperature has on air pressure depends on a few factors, not just those who live in areas with dramatic changes in climate.

As a rule of thumb, tire air pressure will vary 1-2 pounds per square inch – or PSI – whenever the temperature increases or decreases 10 degrees Fahrenheit. Even if you live in an area where winter temperatures aren’t much different from the summer everywhere else, you can still count on there being more than a 10-degree difference in temperature throughout the year, affecting your tire’s air pressure.

![Filling up tire air pressure][6]

How much PSI do I lose in cold weather?

How much of a PSI difference you see in your tires in cold weather is dependent on quite a few factors. We know that PSI fluctuates around 1-2 pounds for every 10 degrees Fahrenheit, but also consider when you put air in your tires in the first place.

Let’s say you filled your tires to 32 PSI on a warm summer day with temperatures around 85 degrees. If the temperature drops to 35 degrees, that’s a 50-degree difference, and your tires may have dropped to 22-27 PSI.

What if you filled your tires to 32 PSI on a 55-degree day and you checked your tires again on a 35-degree day? Well, that’s only a 20-degree difference, and your tire pressure should only drop to around 28-30 PSI.

Should I over-inflate my tires in cold weather?

Your tire pressure is going to drop as the temperature does, so it’s reasonable to consider overinflating your tires to compensate. This is a tactic many people practice, but it is something you want to be very careful of.

Many tire manufacturers recommend adding no more than 3-5 more PSI than normal on some tires in the wintertime. As you know, temperatures can drop significantly throughout the day and at night during this time of year, and having a little more tire pressure than normal can help offset the difference.

This practice is especially useful in areas where there might be as much as a 50-degree difference in temperature during days and nights.

It isn’t something you should immediately do, though. It’s something you should practice only if the manufacturer recommends it. Otherwise, your best bet is to monitor your tire pressure more often during the wintertime. It might be a hassle, but it's worth doing for safety purposes.

How much does tire pressure increase from cold to hot?

Remember the rule of thumb we highlighted earlier? Well, it also applies when the temperature goes up. As temperature climbs, air pressure will rise by approximately 1-2 PSI for every 10 degrees Fahrenheit.

Say you fill a tire to 32 psi on a 35-degree day and check it again on an 85-degree day. The difference of 50 degrees can result in the tire pressure increasing to 37-42 PSI. It’s all relative, so don’t take these values as concrete examples or values.

If you fill those tires to 32 PSI on the same 35-degree day but check them on a 65-degree day, the pressure might only bump up to 34-36 PSI.

Should I inflate to max PSI written on tire or my auto’s suggestion

Never fill your tires to the PSI number on the sidewall of the tire. The number you find there is the max PSI rating, which can lead to catastrophic failure of the tire. Perhaps you won’t see much of an issue outside of poor tire performance initially, but it can cause excessive wear of the tire and eventually a blowout. The suggested PSI rating offered by the tire manufacturer doesn’t consider the specifics of your vehicle.

You want to fill your tire to the PSI rating found in the doorjamb of your vehicle. You might see discrepancies in the PSI rating depending on tire sizes. If so, follow the PSI rating that matches the tire size you are running.

Suppose the tire manufacturer does recommend adding 3-5 more PSI in the wintertime. Your starting point will be the number provided by the auto manufacturer. For example, if the car manufacturer calls for 32 PSI and the tire manufacturer recommends an increase for the winter, fill the tires to 35-37 PSI during the season.

![Working with a tire expert to inspect the tire][7]

Inspect your tires regularly

It may be unspoken, but the number one thing you need to take from this is that tire pressure is not constant. We’re going to bring up that rule of thumb one last time because it does apply to your tires all year long, not just when the seasons change.

It is so important to check tire pressures once a month. Doing so can also help you identify the presence of a slow leak or other tire-related issues you may be experiencing.

Don’t hesitate to give us a call if you have any questions regarding tires and how the environment impacts them. Our reps will help you find the answers to your questions and help you schedule an appointment with a local tire specialist who can set you up with tires that best match your climate.