Why Monthly Is the Right Frequency

Tyres naturally lose air over time — typically 1–3 PSI per month under normal conditions, and more rapidly in cold weather as air contracts. That slow loss rarely triggers a dashboard warning light (most tyre pressure monitoring systems only alert at around 25% below recommended pressure), which means a tyre can be significantly under-inflated without any obvious sign.

Pressure and tread depth directly affect your ability to stop and steer, making them the two most safety-critical tyre measurements you can take. A monthly check takes under 20 minutes and costs nothing beyond a simple gauge. For a broader picture of what these numbers mean on the road, see why tyre pressure is one of the most overlooked safety factors.

This routine also feeds into longer-interval services. Consistent pressure and tread records help you spot problems early — irregular wear logged over two or three monthly checks is a clear signal to schedule rotation, balancing, or alignment before the damage becomes expensive.

Never Read Pressure From a Hot Tyre

Tyre pressure increases as the tyre heats up during driving — sometimes by 4–6 PSI above the cold reading. Checking a hot tyre and releasing air to match the cold spec will leave the tyre dangerously under-inflated once it cools. Always measure pressure when the tyre is cold for a reliable result.

Sidewall Damage Requires Immediate Professional Evaluation

Bulges, deep cuts, or cracks in a tyre sidewall are not cosmetic issues — they indicate structural damage that cannot be repaired. A tyre in this condition can fail suddenly at speed. Do not drive on a visibly damaged tyre; have a qualified tyre technician evaluate it before continuing.

Tools You'll Need

You don't need a workshop full of equipment to complete this inspection confidently. The two non-negotiable tools are a tyre pressure gauge and a tread depth gauge — both are widely available and inexpensive. A portable air compressor or inflator makes the check truly self-contained, so you can correct under-inflation immediately rather than driving to a petrol station.

Required

Tyre Pressure Gauge

Measures tyre inflation in PSI to verify it matches the vehicle manufacturer's specification.

Required

Tread Depth Gauge

Provides an accurate measurement of remaining tread depth in 32nds of an inch.

Optional

Air Compressor or Portable Inflator

Used to add air to under-inflated tyres without needing to visit a filling station.

Optional

Flashlight or Headlamp

Illuminates tyre sidewalls and inner edges to spot damage that is hard to see in shade.

If you already perform other routine checks at home, this inspection pairs naturally with fluid top-ups. Our guide to checking and topping up your car's fluids at home outlines a similarly straightforward process you can run the same day.

The Monthly Inspection Checklist

Work through each tyre systematically — front left, front right, rear right, rear left, then the spare. Taking readings in a consistent order prevents accidental omissions. Record your results each month, even briefly in a notes app; a written log makes irregular wear patterns far easier to spot over time.

Do Not Use the Sidewall PSI Number

The maximum PSI printed on a tyre's sidewall is the tyre's structural limit, not your vehicle's recommended inflation pressure. Using that number will over-inflate your tyres, causing a harsher ride, reduced grip, and accelerated center-tread wear. Always use the pressure listed on your vehicle's door jamb sticker or owner's manual.

Before You Start

Gather a quality tyre pressure gauge (digital or stick-style) and a tread depth gauge before beginning. Must
Check tyres when they are cold — either before the car has been driven or after it has sat for at least three hours. Must
Locate your vehicle's recommended tyre pressure on the driver's door jamb sticker or in the owner's manual. Must
Have a small flashlight handy to inspect tyre sidewalls and inner edges in low-light conditions. Nice to have

Pressure Check

Remove the valve cap from each tyre and set it somewhere safe so it isn't lost. Must
Press the gauge firmly onto the valve stem and read the PSI (pounds per square inch) displayed. Must
Compare the reading to the door jamb specification and add or release air as needed to reach that target. Must
Check the spare tyre pressure as well — a flat spare is useless in an emergency. Should
Replace each valve cap securely after checking to prevent dirt from entering the valve. Must

Tread Depth Inspection

Insert a tread depth gauge into the tyre's main grooves at three points across the tread width — inside, center, and outside. Must
Record the lowest reading for each tyre; the minimum legal tread depth in most US states is 2/32 of an inch. Must
Use the penny test as a quick check: insert a penny with Lincoln's head pointing down — if you can see all of his head, tread is at or below 2/32 inch. Should
Note any differences in readings across the tread width — uneven depth indicates a wear or alignment problem. Should

Visual and Physical Inspection

Walk around the vehicle and visually scan each tyre for bulges, cuts, cracks, or embedded objects such as nails or screws. Must
Inspect the sidewalls for cracking or weathering, which can indicate age-related degradation even if tread depth is adequate. Should
Look for irregular wear patterns: feathering, cupping, or one-sided wear each point to specific mechanical issues worth investigating. Should
Check that all four tyres are the same size and type — mismatched tyres can affect handling and safety systems. Must
Note the tyre age if visible — the four-digit DOT code on the sidewall shows the week and year of manufacture (e.g., 2519 = 25th week of 2019). Most manufacturers recommend replacement after six to ten years regardless of tread depth. Nice to have

If any tyre shows tread depth at or below 4/32 inch (approximately half the legal minimum), start planning for replacement. At that depth, wet-weather braking distances increase meaningfully. Tyre wear patterns also carry history — useful context if you've recently purchased a used vehicle and want to understand how it was previously maintained.