Vehicle maintenance for safety: tires, brakes, lights and warning signs
Simple checks for tires, brakes, lights and dashboard warnings that help prevent crashes
Picture a driver on a rainy evening who brakes for stopped traffic and feels the car keep sliding. The brakes work fine. The worn tires can’t clear the water.
Most crashes start with a human error, but your car’s condition decides how much margin you have to recover. In 2024, 511 people died in tire related crashes, according to the National Highway Traffic Safety Administration (NHTSA) [1].
This guide covers the checks a technician wants every driver to know, plus a 5 minute walk around before each trip and a year round maintenance calendar.
How often do vehicle problems cause crashes?
For NHTSA’s National Motor Vehicle Crash Causation Survey, investigators studied 5,470 crashes from 2005 to 2007 [2]. In about 2% of crashes, they named a vehicle failure as the critical reason, often the last failure in the chain of events [2]. Tires and wheels made up 35% of those cases and brakes 22% [2]. NHTSA cautions that a critical reason is not the cause of a crash or a finding of fault [2].
That 2% likely understates how much upkeep matters. A separate NHTSA analysis of the same survey found tire trouble, such as a flat, blowout or worn tread, just before 9% of crashes [3]. Tires underinflated by 25% or more were 3 times as likely to be cited as a critical event just before a crash [3].
A technician’s reading: worn parts rarely cause crashes alone. But they shrink your margin, so a small mistake becomes a collision.
Tires: the most important check you can make
Set pressure from the door label, not the tire
Find the right pressure on the Tire and Loading Information label on the driver’s door edge or door frame, or in your owner’s manual [1]. NHTSA warns against inflating to the number printed on the tire [4]. That number is the tire’s maximum, not your car’s target.
Check all tires, including the spare, at least once a month and before long trips [1, 4]. Check them cold, meaning the car hasn’t been driven for at least 3 hours [1]. Pressure drops as the air temperature drops, which is why the first cold snap often turns on the warning light [4].
NHTSA says only 19% of consumers properly inflate their tires [1]. Keep a gauge in the glove box. If the tires are warm from driving, don’t let air out. Recheck them later when cold.
What your tire pressure light can and can’t tell you
Since the 2008 model year, passenger cars, light trucks and vans must have a tire pressure monitoring system (TPMS) [1]. A steady light means at least one tire is significantly underinflated [1]. If it flashes for 60 to 90 seconds and then stays on, the system itself has a fault [1].
The federal standard requires a warning when a tire falls 25% below the recommended cold pressure or to a set minimum, whichever is higher [5]. On a car labeled 35 psi, a tire could drop to about 26 psi without a warning (our calculation).
Some systems warn even later: in AAA’s 2023 tests of 11 recent vehicles, 5 warned at 75% of the posted pressure [6]. Five more warned at about 70% to 73%. One gave no warning even at 65% [6].
TPMS still helps. In NHTSA’s evaluation of 2004 to 2007 models, 23.1% of vehicles without TPMS had a severely underinflated tire, compared with 11.8% of those with it [7]. Federal rules require owner’s manuals to say TPMS does not replace regular pressure checks [5].
Tread: 2/32 inch is the floor, 4/32 is the smarter line
NHTSA says tires are unsafe and should be replaced at 2/32 inch of tread, when the tread wears level with the raised indicator bars in the grooves [1]. In the penny test, put Lincoln’s head upside down in a groove. If you can see the top of his head, replace the tire [1].
AAA recommends replacing tires sooner, at 4/32 inch [8]. In AAA’s 2018 tests on wet pavement at 60 mph, tires worn to 4/32 inch added an average of 87 feet of stopping distance, a 43% increase [8]. When cars on new tires had stopped, cars on worn tires were still moving at 40 mph [8].
At 60 mph, a car covers about 88 feet per second. So those extra 87 feet equal about a full second of highway travel (our calculation). For a quick check, AAA suggests an upside down quarter: if you can see all of Washington’s head, start shopping [8].
NHTSA’s crash survey also looked at tire problems just before a crash. Vehicles with 0 to 2/32 inch of tread had them 3 times as often as those with 3 to 4/32 inch [3]. See our guide to driving in rain and hydroplaning.
Read the wear pattern
Technicians read uneven wear this way:
- Both outer edges worn: usually underinflation.
- Center worn: often overinflation.
- One edge worn: often an alignment problem.
- Scalloped dips: often worn shocks or struts, or an unbalanced wheel.
NHTSA advises rotating tires every 5,000 to 8,000 miles, or sooner if uneven wear appears [1]. Balancing keeps wheels from shaking. Alignment keeps the car tracking straight [1].
Age, damage and the spare
Rubber ages even with deep tread. Some vehicle and tire makers recommend replacing tires that are 6 to 10 years old, regardless of tread [1]. Heat, sunlight, poor storage and low mileage raise the risk. Spares age because they’re rarely replaced [1].
The last 4 digits of the DOT Tire Identification Number (TIN) on the sidewall show the week and year a tire was made [1]. For example, 2523 means the 25th week of 2023.
Look for cuts, punctures, bulges and cracks [4]. A bulge means internal damage, so replace that tire before driving at speed.
Use a full size spare in place of a worn tire only in an emergency, such as a flat [1]. A compact spare is for short, slow trips. Follow the limits printed on it or in your manual.
Size, load, speed rating and registration
Replacement tires should match the size in your manual or on the door label [1]. Technicians also match the load index and speed rating printed after the size. A lower rating may not suit your vehicle. The door label also lists your vehicle’s limit for people and cargo.
Register new tires through the retailer, by mail or online with the TIN. That way, the manufacturer can reach you in a recall [9].
Brakes: warning signs you shouldn't ignore
Have your brakes inspected soon if you notice any of these:
- A high pitched squeal: many pads have a metal tab that squeals when they’re nearly worn out.
- Grinding: the pads may be gone and the rotors are being damaged.
- Pulling to one side when you brake.
- A soft, spongy or sinking pedal, or one that sits lower than usual.
- Pulsing through the pedal or steering wheel.
- Longer stops than usual, or a hot, burning smell.
The red brake light needs attention right away. Under federal rules, it signals a set parking brake, a big loss of fluid or pressure, or certain electrical failures [10]. A separate yellow ABS light means the antilock system has a fault [10]. Regular brakes usually still work, but without antilock help.
Check the brake fluid level with your other fluids [11]. Because brake fluid absorbs moisture, replace it on your manual’s schedule. A level that keeps dropping points to a leak or worn pads.
Lights: see and be seen
Once a month, check low and high beams, brake lights, turn signals, hazard flashers and interior lights, plus trailer lights if you tow [4, 11]. If you’re alone, back up near a garage door at night and watch for the brake light glow.
In AAA tests, clouded or yellowed headlights produced only 20% of the light of new ones. Lenses can fade within 3 to 5 years [12]. Restoration brought back about 70% of the light. Replacement restored the most [12].
Aim matters too. The Insurance Institute for Highway Safety (IIHS) reported one SUV’s headlights went from poor to good solely through the automaker’s aim changes [13]. Ask a shop to check aim after front end repairs or if oncoming drivers often flash you.
Replace burned out bulbs promptly, ideally in pairs so both sides match. See our night driving guide.
Wipers, glass, defrosters and mirrors
Replace wiper blades when they streak, chatter or skip. Inspect the rubber for cracks or warping [11]. Before winter, fill the washer reservoir with winter fluid that has a deicer. Also make sure every defroster works [4].
Chips can spread into cracks, so repair them early. Replace glass cracked in your line of sight. If a driver assistance camera sits behind the windshield, ask whether replacement includes recalibrating it. Keep mirrors and the inside of the glass clean to cut night glare.
Under the hood: what you can check and what to leave to a pro
NHTSA advises checking the oil periodically and keeping the brake, transmission, power steering and washer fluid reservoirs full [11]. Coolant should meet the automaker’s spec. A mechanic should test it and look for leaks [4]. Inspect belts and hoses for bulges, blisters, cracks and cuts [11].
Comparison compiled by Safety Behind the Wheel Foundation
| Item | What you can check | Leave to a technician |
|---|---|---|
| Engine oil | Dipstick level, engine off, car on level ground | Changes on your manual’s schedule; leaks |
| Coolant | Level in the overflow tank, engine cold | Leaks, testing, flushing; never open a hot radiator cap |
| Brake fluid | Level between the min and max marks | Fluid replacement, leaks and any brake repair |
| Power steering fluid (hydraulic systems) | Level | Leaks; whining or stiff steering |
| Washer fluid | Top off often | None |
| Belts and hoses | Bulges, blisters, cracks or cuts | Replacement |
| Battery | Corrosion, loose cables, slow cranking | Testing the battery and charging system |
Cold weather cuts battery power. Gas and diesel engines need more of it to start [4]. Heat wears batteries out too. If the engine cranks slowly, have a mechanic test the battery before winter [4]. Also make sure floor mats fit and are clipped in so they can’t jam the pedals [11].
Dashboard warning lights: a quick guide
Automakers commonly use traffic light colors. Red means stop when it’s safe and find out why. Yellow or amber means get it checked soon. Symbols vary, so keep your manual handy.
Comparison compiled by Safety Behind the Wheel Foundation
| Light | Usual color | What to do |
|---|---|---|
| Brake system | Red [10] | Make sure the parking brake is fully off. If the light stays on, stop safely; don’t drive on a soft pedal. |
| Oil pressure | Red | Pull over and shut off the engine. Check the oil level; don’t drive until it’s fixed. |
| Engine temperature | Red | Pull over and shut off the engine. Let it cool before opening anything. |
| Charging system (battery symbol) | Red | Turn off accessories and head straight for help; the car may stall. |
| Airbag | Red or amber, varies | The airbags may not work as designed. Get service soon. |
| ABS | Yellow [10] | Normal braking remains. Brake gently and get it checked soon. |
| Tire pressure (TPMS) | Amber [6] | Check all tires with a gauge. Flashing, then steady, means a system fault [1]. |
| Check engine, steady | Yellow or amber | Make sure the fuel cap is tight and schedule a diagnosis. |
| Check engine, flashing | Yellow or amber | Usually a severe misfire that can overheat the exhaust system. Ease off and get service right away. |
Your pre trip walk around and maintenance calendar
The 5 minute walk around
A year round calendar
Your owner’s manual schedule comes first. This calendar fills the gaps.
Comparison compiled by Safety Behind the Wheel Foundation
| When | What to do |
|---|---|
| Every fill up | Glance at the tires, top off washer fluid, note any warning lights |
| Monthly | Gauge all tires cold, including the spare; tread check; lights walk around; fluid levels |
| Every 5,000 to 8,000 miles | Rotate tires if your manual calls for it; have brakes, belts and hoses inspected |
| Fall | Battery and charging test, coolant check, winter washer fluid, new wipers, test defrosters |
| Spring | Replace winter worn wipers, check alignment after pothole season, test air conditioning |
| Once a year | Check headlight lenses and aim, read tire age codes, ask about brake fluid, run a recall check |
| Before long trips | Full walk around plus a cold tire pressure check |
EVs, hybrids, older vehicles and new drivers
Electric and hybrid vehicles: Battery weight and quick acceleration can wear tires faster, so check tread often and match the original load rating. Regenerative braking does much of the slowing, but the regular brakes still need inspection. Most EVs also have a 12 volt battery. If it dies, the car may not start. Use technicians trained on high voltage systems.
Older vehicles: AAA reported in 2018 that vehicles 10 or more years old were twice as likely to strand drivers [14]. They were also 4 times as likely to need a tow [14]. Battery, cooling system and tire problems were most common [14]. Watch parts that age with time: hoses, belts, wipers and tires.
Teens and parents: Before a new driver goes solo, do the checks together. Find the door label, use the gauge, do the quarter test and name each warning light. Make the monthly tire check the teen’s job. Agree that red lights or brake noises get reported the same day, without blame.
Recalls: the free safety fix
Search NHTSA’s recall site with your 17 character vehicle identification number (VIN), found at the lower left of the windshield or on your registration [15]. Recall repairs are free at the dealer. NHTSA’s SaferCar app can alert you to new recalls [15]. The search won’t show recalls older than 15 years unless the manufacturer offers more coverage [15].
Tires get recalled too, which is why registering them matters [1, 9]. See our guide to vehicle recalls and safety defects.
Frequently asked questions
How often should I check my tire pressure?
At least monthly and before long trips, with the tires cold [1, 4]. Include the spare, and check more often in cold months, when pressure drops [4].
Is it safe to drive with the tire pressure light on?
A steady light means at least one tire is significantly low [1]. Slow down, drive gently to the nearest air pump and fill to the label pressure. If the light comes back, have the tire checked for a leak.
When should I replace my tires?
Replace them at 2/32 inch of tread at the latest. AAA recommends 4/32 inch for better wet road stopping [1, 8]. Replace any tire with a bulge or sidewall damage right away. Ask a technician about tires more than 6 years old [1].
Can I keep driving with the check engine light on?
If the light is steady and the car drives normally, you can usually get to a shop within a few days. A flashing light usually signals a serious misfire, so slow down and get service right away.
Do electric cars need less maintenance?
EVs skip oil changes, but they still need tire, brake, light, wiper and 12 volt battery checks. Their extra weight makes tire care especially important.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Build three habits: check tire pressure and tread monthly, walk around to check your lights, and act fast on red warning lights or brake noises. These few minutes a month cover the parts most often linked to vehicle related crashes.
Related articles
- Driving in rain: hydroplaning, standing water and flood safety
- Night driving safety: how to see hazards and stop in time after dark
- Vehicle recalls and safety defects: how to check, fix and report
- Roadside breakdown safety: what to do when your car breaks down
- Choosing a safe first car for your teen: what matters most
Sources and further reading
- 1National Highway Traffic Safety Administration (NHTSA). Tire Safety Ratings and Awareness (TireWise). No date shown; accessed October 2026. nhtsa.gov/vehicle-safety/tires
- 2National Highway Traffic Safety Administration (NHTSA). Critical Reasons for Crashes Investigated in the National Motor Vehicle Crash Causation Survey. DOT HS 812 115. February 2015. crashstats.nhtsa.dot.gov/…/812115
- 3National Highway Traffic Safety Administration (NHTSA). Tire-Related Factors in the Pre-Crash Phase. DOT HS 811 617. April 2012. crashstats.nhtsa.dot.gov/…/811617
- 4National Highway Traffic Safety Administration (NHTSA). Winter Weather Driving Tips. No date shown; accessed October 2026. nhtsa.gov/winter-driving-tips
- 5NHTSA. 49 CFR 571.138, Federal Motor Vehicle Safety Standard No. 138: Tire Pressure Monitoring Systems. Electronic Code of Federal Regulations, current as of September 28, 2026. ecfr.gov/…/section-571.138
- 6AAA. Don’t Let Your Tire Pressure Monitoring System Leave You Feeling Flat. October 23, 2023. newsroom.aaa.com/2023/10/…
- 7National Highway Traffic Safety Administration (NHTSA). Evaluation of the Effectiveness of TPMS in Proper Tire Pressure Maintenance. DOT HS 811 681. November 2012. crashstats.nhtsa.dot.gov/…/811681
- 8AAA. Tread Lightly: Worn Tires Put Drivers at Risk. June 7, 2018. newsroom.aaa.com/2018/06/…
- 9National Highway Traffic Safety Administration (NHTSA). Congratulations on Your New Tire Purchase (consumer brochure, 10753a-051214-v2). Accessed October 2026. nhtsa.gov/node/35306
- 10NHTSA. 49 CFR 571.135, Federal Motor Vehicle Safety Standard No. 135: Light Vehicle Brake Systems. Electronic Code of Federal Regulations, current as of September 29, 2026. ecfr.gov/…/section-571.135
- 11National Highway Traffic Safety Administration (NHTSA). Summer Driving Tips. No date shown; accessed October 2026. nhtsa.gov/summer-driving-tips
- 12AAA. AAA Illuminates the Dangers of Driving with Cloudy Headlights. December 11, 2018. newsroom.aaa.com/2018/12/…
- 13Insurance Institute for Highway Safety (IIHS). Good IIHS headlight ratings linked to lower crash rates. October 14, 2021. iihs.org/news/detail/…
- 14AAA. Double Digits Means Double Trouble for Vehicle Breakdowns. April 17, 2018. newsroom.aaa.com/2018/04/…
- 15National Highway Traffic Safety Administration (NHTSA). Recalls. No date shown; accessed October 2026. nhtsa.gov/recalls
This article reflects the safety priorities of automotive service and vehicle safety engineering. It is general education, not mechanical, legal or professional advice for any individual vehicle. Your owner’s manual and a qualified technician come first. Laws, data and vehicle features change, so verify details with official sources. Reviewed October 2026.
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