Many drivers assume that as long as the tire looks round, it’s fine. But tire pressure is about much more than appearance. It is the single most important factor affecting your vehicle’s safety, fuel economy, and handling.
Driving on tires that are over- or under-inflated by just a few PSI can shorten their lifespan by thousands of kilometres and cost you extra at the gas pump. Here is everything you need to know to get it right.
Where to Find the Recommended Tire Pressure?
The biggest myth in car maintenance is that the correct pressure is written on the tire itself. This is false. The number stamped on the sidewall of your tire is the Maximum Permissible Pressure—not the recommended driving pressure.
To find the correct numbers for your specific vehicle, look for the Tire and Loading Information Placard. It is usually located in one of these spots:
- Driver’s side door jamb (the most common spot)
- Inside the glove box door
- Inside the fuel filler door
- Your Owner’s Manual
If you have upgraded your wheels or are driving a modified vehicle, the factory sticker might no longer apply. In complex cases like these, it is best to consult with auto experts to determine the safe range for your custom setup.
Factors That Change Your Tire Pressure
Tire pressure isn’t static; it changes with the environment and how you use your car.
1. Temperature (The “10-Degree Rule”)
In Edmonton, this is the #1 reason for low tire pressure warnings. Air contracts when it gets cold. A good rule of thumb is that for every 10°F (or 5°C) drop in temperature, your tire pressure drops by 1 PSI. This means if you last filled your tires in August and haven’t checked them since, your tires are likely dangerously low by the time the first snow falls. This physics applies to all rubber, but knowing the difference between all season and all weather tires can help you understand how different compounds handle these temperature swings.
2. Vehicle Load
If you are planning a road trip with a fully loaded trunk or towing a trailer, you may need to increase your rear tire pressure to compensate for the extra weight. Always check your manual for “Loaded” vs. “Normal” pressure specs.
How to Check Tire Pressure Correctly
To get an accurate reading, you must check your tires when they are “Cold.” This doesn’t refer to the weather, but to the friction heat. Drive less than 2 kilometres or let the car sit for at least 3 hours before checking.
Tools you can use:
- Stick Gauge: Cheap and durable.
- Digital Gauge: More precise and easier to read.
- TPMS (Tire Pressure Monitoring System): Most modern cars warn you automatically.
However, electronic systems aren’t perfect. Sometimes a malfunction in the TPMS can trigger dashboard warnings that won’t go away. If you are dealing with persistent dashboard errors after servicing your wheels, you might need to learn how to turn off your check engine light after a repair or reset your sensors manually.
The Risks of Wrong Pressure
Why fuss over a few PSI? Because the consequences affect both your wallet and your safety.
| Issue | Under-Inflation (Too Low) | Over-Inflation (Too High) |
| Tire Wear | The edges of the tire wear out fast. | The center of the tire wears out fast. |
| Handling | Sluggish steering; poor cornering. | Harsh ride; loss of traction. |
| Safety Risk | Overheating leading to blowouts. | High risk of puncture from potholes/debris. |
| Economy | Increased rolling resistance (wastes fuel). | No benefit. |
Tire pressure is the easiest maintenance task, yet it is the most neglected. We recommend checking your pressure once a month and before any long highway trips.
If you don’t have a gauge, or if your TPMS light is on and you are unsure why, swing by Driver Tires. We offer a full range of automotive services, from simple pressure checks to suspension repairs, ensuring your vehicle is safe for the road ahead.