🛞 Tire Pressure Guide

Tire pressure is the single most overlooked piece of vehicle maintenance. Studies show that roughly one in four vehicles on the road has at least one significantly under-inflated tire — yet checking takes less than five minutes and the consequences of getting it wrong affect your safety, your fuel economy, and how long your tires last. Here's everything you need to know.

Where to Find the Right Tire Pressure

The most important thing to know about tire pressure: the number on the tire sidewall is NOT your target pressure. That number is the maximum pressure the tire can hold — not the recommended pressure for your vehicle.

Your vehicle's recommended tire pressure is printed on the driver's door jamb sticker — a label on the door frame or inside the door. It specifies the PSI (pounds per square inch) or kPa for your front and rear tires. This is the number your manufacturer engineered for ride quality, handling, fuel efficiency, and safety on your specific vehicle.

How Temperature Affects Tire Pressure

Tire pressure changes with temperature — roughly 1 PSI for every 10°F (5-6°C) change in ambient temperature. This is why your TPMS light often comes on in the fall when temperatures first drop significantly overnight.

This means a tire at 32 PSI in summer can drop to 26–27 PSI by midwinter — significantly underinflated. This is why you should always check and adjust tire pressure when seasons change, not just once a year.

How to Check Tire Pressure Correctly

Checking tire pressure takes about 2 minutes and requires only a tire pressure gauge (available at any auto parts or hardware store for $5–$20). Here's the correct procedure:

1. Check when tires are "cold" — meaning the car has been parked for at least 3 hours or driven less than 1.5 km. Driving heats the air inside tires, raising pressure 4–6 PSI above the true resting pressure.
2. Remove the valve stem cap from one tire.
3. Press the gauge firmly onto the valve stem until no air is hissing out.
4. Read the pressure. Compare it to the recommended PSI from your door jamb sticker.
5. Add air if low (most gas stations have air compressors). Release air if over-inflated by pressing the centre pin in the valve stem with a pen or key.
6. Replace the valve cap and check the remaining three tires.

What Is TPMS and What Does the Light Mean?

TPMS stands for Tire Pressure Monitoring System. It's been required on all new vehicles in the US and Canada since 2008. The system uses sensors inside each wheel to monitor pressure and alert you when any tire drops significantly below the recommended level.

When the TPMS Light Comes On

The TPMS warning light — a cross-section of a tire with an exclamation point — illuminates when one or more tires is 25% or more below the recommended pressure. At 32 PSI recommended, that means 24 PSI or lower. By the time the light comes on, you're already significantly underinflated.

Don't wait for the TPMS light — check pressure monthly so you catch a slow leak or seasonal drop before it gets that bad.

TPMS Light After Filling Tires

After inflating your tires, the TPMS light should go off within a few minutes of driving. If it stays on, one of three things may be happening:

• One tire is still underinflated — re-check all four
• A TPMS sensor battery has died — sensors last 5–10 years and need periodic replacement
• A sensor was damaged (common after a tire change if the shop wasn't careful)

Effects of Incorrect Tire Pressure

Underinflated Tires

• Reduced fuel economy: underinflated tires create more rolling resistance. Tires 8 PSI low can reduce fuel economy by 4–8%.
• Uneven tread wear: the outer edges of the tread wear faster, shortening tire life.
• Increased risk of blowout: a seriously underinflated tire generates excess heat, which can cause sudden failure at highway speed.
• Reduced handling: the tire is less responsive and takes longer to stop.

Overinflated Tires

• Harsh ride: overinflated tires transmit more road imperfections to the cabin.
• Centre tread wear: the middle of the tread bears too much load and wears faster.
• Less grip: the tire contact patch shrinks, reducing traction especially in wet conditions.
• Vulnerability to damage: an overinflated tire is more prone to damage from potholes or road debris.

How Often Should You Check Tire Pressure?

The simple answer: once a month, and every time you notice a significant temperature change (more than 10°C from normal). Also check whenever you notice any of these:

• The car feels different to drive — squishy, pulling, or bouncy
• Noticeably lower fuel consumption than usual
• The TPMS light comes on
• You've added or removed a passenger load or cargo