Chinook rolls in overnight. Temperature jumps 25°C. You start the car in the morning and the little tire-pressure light is on.
Sound familiar? Tire pressure is one of the few things on your car that Calgary’s weather actively messes with. Not just once a season — sometimes twice in the same week.
Here’s what’s going on, and the 5-minute check that saves most people from an expensive tire.
Why Calgary tires can’t sit at one pressure
Air expands with heat and shrinks with cold. That’s the physics part. In practical terms: your tires lose or gain roughly 1 psi for every 5–6°C the temperature moves.
Calgary swings that much on a normal weekday in June. It swings much harder than that when a chinook drops in.
A tire set to 34 psi at 8 AM on a cool July morning can read 40+ psi by mid-afternoon. That same tire, checked at −20°C on a January night, can be down to 26 psi. Neither is the “correct” reading — the tire hasn’t changed, the air inside it has.
The one that catches people: driving on hot asphalt for two hours can add another 3–4 psi on top of ambient. That’s normal. It’s why you always check pressure cold, before you drive.
The 5-minute check
Do this once a month, and once after any big temperature swing.
- Park in the shade, cold — first thing in the morning is easiest.
- Look at the sticker on the driver’s door jamb. That’s the number you want. It’s not the number on the tire sidewall — the sidewall number is the maximum the tire can hold, not the pressure the car is designed to run.
- Unscrew the valve cap. Press a pencil-style gauge or a good digital gauge straight down until the hiss stops.
- Read the number. Compare to the door-jamb spec.
- Add air if you’re more than 2 psi low. Most gas station pumps read close enough; the tire-shop hoses are usually more accurate.
Don’t forget the spare. We’ve pulled cars in where the spare’s been sitting at 15 psi for three years and the owner had no idea until they needed it.
Seasonal cadence — what to check when
Spring (April–May). Once winter releases, check every tire. Winter cold pulls pressure down slowly; a lot of drivers don’t notice until spring tires go on and they’re 4 psi low.
Summer (June–August). Check at the start of the month. Then again before any road trip. Heat makes small under-inflation problems into big blowout problems fast.
Fall (September–October). Right after the first cold night. That’s when the TPMS light usually comes on for the first time.
Winter (November–March). Check every 2–3 weeks. Cold snaps and chinook flips mean pressure moves a lot. And winter tires themselves lose pressure slightly faster than summer tires do.
If you’re on seasonal changeovers with us, pressure gets set correctly for the new season when the swap happens.
What the TPMS light actually means
The tire pressure monitoring system lights up when one or more tires drop about 25% below spec. In practice, on most cars, that’s around 6–8 psi low.
A steady light means one tire is low. Check them all and top up.
A blinking light — or a light that stays on after topping up — means something’s wrong with the sensor itself. Sensors have batteries that last 5–10 years, and once one dies it usually needs replacing rather than resetting.
The light coming on after a hard cold snap is usually just the cold. Top up and it goes off within a few kilometres of driving. The light coming on in summer usually means an actual slow leak.
When to bring it in
If you top up a tire and it’s low again in a week, that’s a leak — not something to keep chasing with the pump. Nails, sidewall damage, a slow valve-stem leak, or a bad seal at the wheel bead all look the same from the driver’s seat.
Call us at (403) 243-4204 and we’ll check it, patch it if we can, or tell you honestly if it needs replacing. Slow leaks are cheap to fix. Running on 24 psi for six months ruins the tire and you end up buying a new one. More on our tire services here.
FAQ
How often should I check my tire pressure in Calgary?
Once a month is a good baseline. Add a check any time the temperature swings hard — a summer heat spike, the first fall cold snap, or a chinook flip in winter.
Does the TPMS light coming on mean my tire is damaged?
Usually not. Most of the time it’s just cold weather pulling pressure below the alert threshold. Top up to the door-jamb spec and drive — if the light comes back within a few days, that’s when to have it checked.
What pressure should my tires actually be at?
Whatever the sticker on your driver’s-side door jamb says for your vehicle. Not the number on the tire sidewall — that’s the maximum, not the recommended. If the sticker is missing, the owner’s manual has it.
If you’re not sure what’s normal for your car or how much pressure loss is too much, stop by the shop or give us a call — we’ll take a look and tell you straight.