Living in Ottawa, we have a wide array of seasonal temperatures, and we get out there and embrace all of them. Summer here is bright and warm and occasionally more humid than anywhere else on the planet. In the fall, we have the most beautiful crisp days imaginable, and everyone is outside, soaking it in. As the winter hits, we deal with some of the dampest, coldest, snowiest weather anywhere in the country like pros. And by spring, melting rains and longer days make us feel like we’re born again.
Of course, all of this change means added stress for your vehicle. Driving in one season, in Ottawa, is nothing like driving in another. And, when it comes to your tires, you need to know how they are going to respond no matter what mother nature throws your way.
If you’ve been in Ottawa for more than a year, you already know too well the need for winter tires from November to March. However, do you understand how the variations in seasonal temperatures can affect the rubber you’re rolling on? Knowing this may just change the way you approach the road and help keep you safe on your way from A to B.
Winter Vs. Summer
We’ll begin with a quick recap of the difference between winter and summer tires. The critical thing to remember here is how the rubber compounds in your tires change with the thermostat. When the outside temperature regularly stays below 7-degrees, the rubber in your all-season or summer tires becomes more rigid. The same compounds that work so well in the heat become inflexible in the cold. And, when the rubber stiffens, its ability to move with and grip the surface of the road is severely diminished.
Of course, having seasonal tread pattern designs are incredibly helpful also. However, the most significant reason for changing your tires is to ensure that the rubber can remain supple and respond to the road’s challenges.
In the summer you have the opposite problem. Winter tires are made of much more supple rubber, and in the heat of an Ottawa summer, they almost start to melt. Not only does this make for a really soft ride, but your handling can become dangerously impaired. Not to mention, rolling on winter tires through the summer is going to shred through the rubber and drastically shorten their lifespan.
Air Pressure
Maintaining proper tire pressure is fundamental in allowing your tires to perform safely and at their best at any time of year. However, as the temperature changes, it can cause your tire’s internal pressure to fluctuate. For this reason, we recommend checking your tire pressure at least once a week and making adjustments as required.
Of course, why the air pressure in your tires changes with the weather is a matter of chemistry and could be the perfect way to get teenagers talking about science. However, the simple explanation is that as the outside temperature warms, the air in your tires expands to take up more volume, meaning the same air fills more space. On the other hand, when the temperature cools, the air molecules shrink and take up less area, which means you need more air to fill the same tire. For this reason, your car’s sensors will often notify you that your tires are underinflated in the autumn as the air starts to chill, even though nothing has leaked. Generally, the inflation pressure in tires will drop by about one to two psi for every 10 degrees the temperature decreases.
Now, as you drive your car, and the rubber warms up, the pressure in the tires will increase. You can usually expect a one-psi increase during each five-minute interval of the first 15 to 20 minutes you’re driving. And, while you may well get the pressure back to the manufacturer’s recommended psi, which will likely satisfy the sensor, you will still need to make an adjustment. The recommended psi is always calculated when the tires are cool, and ideally, when you add air to them, it should be before you warm them up. However, since most people don’t have an air compressor at home, you will probably have to drive to a service station to top them up. To compensate for the tires warming, make sure you measure the tire pressure before leaving home and make a note of it. When you arrive at the gas station, measure the tires again, and add the amount of air you need based on the first “at home” reading.
Whether your tires are overinflated or underinflated can have serious safety consequences, affect the performance, and reduce your vehicle’s fuel efficiency.
When it comes to overinflated tires, the trouble is they become inflexible, resulting in a reduced surface area contacting the road. With more rigid rubber, the tires have a decreased capacity to absorb shocks from imperfections in the street and are more likely to rupture if you run over a pothole. The reduction in contact area created by overinflation causes uneven tread wear, usually referred to as “centre wear.” This means tires end up smooth in the middle with more tread on the outside edges, leading to a decrease in traction and an increased stopping distance.
With underinflated tires, the rubber has trouble holding its shape, and too much surface area comes into contact with the road. This extra drag, or rolling resistance, causes an increase in fuel consumption. According to research by the US Department of Energy, for every 1-psi drop in pressure, you can expect your gas mileage to lower by 0.4 percent. If that wasn’t bad enough, underinflation also creates “shoulder wear.” This irregular wear pattern is the opposite of “centre wear,” in that there is a strip of regular tread down the center of the tire, while the shoulders become smooth and worn down. With the combination of soft rubber and “shoulder wear” resulting from underinflation, you will notice reduced agility and considerable understeer. All of which makes underinflated tires feel mushy and unresponsive as you drive.
Driving in a city like Ottawa presents its own series of challenges. And with our dramatic swing in annual temperatures, it puts additional monitoring responsibilities on car owners to ensure their vehicles are performing at their best and as safe as possible.
Regular tire inspection is critical to ensure that your vehicle is ready to handle whatever the weather dishes out. If you have questions about the state of your wheels or want to talk to our specialists about preventative maintenance, give us a call or drop by. We love to talk shop.
Below we’re including our guide to checking your tire pressure, in case you or anyone you know needs a quick refresher as the seasons change.
Our Guide to Checking Your Tire Pressure
- Tire Pressure should be checked “cold” before you’ve driven the car or about three hours after to ensure an accurate read
- Remove the valve cap from the valve stem – (If the cap is missing, be sure to pick up a replacement to prevent debris from building up in the connector)
- Press the head of your pressure gauge onto the end of the valve stem to get a reading (it’s typical to hear air hissing when you press the gauge)
- As soon as you get a number (either on the digital screen or on the stick of a pencil-style tire gauge) remove the device from the stem
- If the pressure is too high, use the nob on the back of the gauge to press the pin into the valve stem and release some air and repeat test
- If the tire is underinflated, take the vehicle to the nearest gas station or auto garage, add some air and repeat the test
