# Inside a Smog Check Station and a Tire Shop: A Photo and Video Tour A California smog check on a 2000 or newer car is mostly a computer check: the inspector plugs the state BAR-OIS system into the OBD-II port under the dashboard, looks over the emission parts and checks the gas cap, then the result goes straight to the state. In a tire shop, a tire changer takes the old tire off the rim, a balancer spins the wheel to place small weights, and an alignment rack measures the wheel angles with sensors clamped to each wheel. The photos and videos below show each step. ## Part 1: the smog check station ### The inspection lane Emission testing in the United States started in the 1970s with lanes like this one. Inspectors drove each car in, ran the engine and measured what came out of the tailpipe. ![Inspectors test a car in the lane of a 1975 auto emission inspection station in Norwood, Ohio](https://appointauto.com/media/field/smog-lane-1975.jpg) An emission inspection lane in Norwood, Ohio, in 1975: one of the first programs of its kind. Photo: [Lyntha Scott Eiler, U.S. EPA DOCUMERICA (National Archives)](https://commons.wikimedia.org/wiki/File:OVERALL_VIEW_OF_THE_SAFETY_LANE_AT_AN_AUTO_EMISSION_INSPECTION_STATION_IN_NORWOOD%2C_OHIO._ONE_EMPLOYEE_OF_THE_PUBLIC..._-_NARA_-_557852.jpg), [Public domain](https://commons.wikimedia.org/wiki/Help:Public_domain), Wikimedia Commons ### Tailpipe probe for older cars A probe in the tailpipe measures hydrocarbons, carbon monoxide and other gases. In California, cars from 1999 and older still get a tailpipe test, so the visit takes longer and can cost more. ![Exhaust probe in the tailpipe of a car during a 1975 emission test in Norwood, Ohio](https://appointauto.com/media/field/smog-tailpipe-1975.jpg) The exhaust probe goes into the tailpipe. Older cars in California are still tested this way. Photo: [Lyntha Scott Eiler, U.S. EPA DOCUMERICA (National Archives)](https://commons.wikimedia.org/wiki/File:CAR_BEING_CHECKED_AT_AN_AUTO_EMISSION_INSPECTION_STATION_IN_NORWOOD%2C_OHIO._THE_TEST_INCLUDES_A_CHECK_OF_THE_EXHAUST..._-_NARA_-_557848.jpg), [Public domain](https://commons.wikimedia.org/wiki/Help:Public_domain), Wikimedia Commons ### The plug-in test for 2000 and newer Newer cars watch their own emissions. The inspector connects the state system to the OBD-II port, usually under the dashboard near the steering column, and reads whether the monitors are ready and whether there are stored trouble codes. That is why a [check engine light](https://appointauto.com/guides/check-engine-light-smog-check/) or a recently disconnected battery can mean a fail. ![OBD-II diagnostic connector under a car dashboard](https://appointauto.com/media/field/obd-port.jpg) The OBD-II port. This is what the smog inspector plugs into on a 2000 or newer car. Photo: [0x010C](https://commons.wikimedia.org/wiki/File:2016-07_ODB-II_connector_01.JPG), [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/), Wikimedia Commons [Video: Smog Check Inspection Using the BAR-OIS](https://www.youtube.com/watch?v=IdUJb9VSzjY) California's Bureau of Automotive Repair shows a complete Smog Check on the BAR-OIS, the system every licensed station uses. Watch it to see the visual check, the plug-in test and how the result is sent to the state. Video: Bureau of Automotive Repair · YouTube · 13:08 ### The result The station sends a pass straight to the DMV, plus the $8.25 certificate. If the car fails, you get a report that lists why. Read [what to do after a failed smog check](https://appointauto.com/guides/failed-smog-check-what-next/), including state repair help. ![A driver hears that her car failed the emission test, Norwood, Ohio, 1975](https://appointauto.com/media/field/smog-failed-1975.jpg) A driver hears that her car failed the test (1975). Today the failure report lists the exact reason. Photo: [Lyntha Scott Eiler, U.S. EPA DOCUMERICA (National Archives)](https://commons.wikimedia.org/wiki/File:MOTORIST_RECEIVES_THE_BAD_NEWS_THAT_HER_CAR_HAS_FAILED_THE_TEST_AN_AUTO_EMISSION_INSPECTION_STATION_IN_NORWOOD%2C_OHIO...._-_NARA_-_557863.jpg), [Public domain](https://commons.wikimedia.org/wiki/Help:Public_domain), Wikimedia Commons [Video: Regular Smog Check vs STAR Smog Check](https://www.youtube.com/watch?v=7vmp_vKeRjE) A California smog station explains that the test is the same at a STAR station. STAR is a performance standard for the station, and the DMV sends some cars to STAR stations. Video: Pass 'N Go Smog Center · YouTube · 1:04 ## Part 2: the tire shop ### The bay A typical tire bay has a tire changer, a wheel balancer, an air supply and racks of tires. Many shops also have an alignment rack. ![Inside a tire shop: tire changer, wheel balancer, tools and parts bins](https://appointauto.com/media/field/tire-shop.jpg) Inside a working tire shop: the tire changer on the left and the balancer on the right. Photo: [Visitor7](https://commons.wikimedia.org/wiki/File:Inside_a_Tire_Shop.jpg), [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/), Wikimedia Commons ### Mounting the tire The tire changer clamps the wheel, breaks the bead and lifts the old tire off without scratching the rim. The new tire goes on the same way, then it is inflated to the pressure on your door-jamb sticker. Ask for new valve stems or TPMS service kits, which are often a small extra charge (see [tire installation costs](https://appointauto.com/guides/new-tire-installation-cost/)). ![Tire changer machine in a tire shop with new tires racked behind it](https://appointauto.com/media/field/tire-changer.jpg) A tire changer, with new tires stocked behind it. Photo: [Flippin504](https://commons.wikimedia.org/wiki/File:Tire_Changer.jpg), [CC BY 3.0](https://creativecommons.org/licenses/by/3.0/), Wikimedia Commons ### Balancing The balancer spins the wheel and shows where small weights go so it rolls smoothly. Unbalanced wheels cause vibration at highway speeds. ![Wheel balancing machine at a tire service shop](https://appointauto.com/media/field/wheel-balancer.jpg) A wheel balancer. The screen shows where to place the weights. Photo: [Shixart1985](https://commons.wikimedia.org/wiki/File:Modern_car_wheel_balancing_machine_tool_at_tire_service.jpg), [CC BY 2.0](https://creativecommons.org/licenses/by/2.0/), Wikimedia Commons [Video: What is Tire Balancing?](https://www.youtube.com/watch?v=d-z2ZoQ9sB4) Discount Tire explains static and dynamic imbalance, standard balancing versus Road Force balancing, and how often tires should be balanced. Video: Discount Tire · YouTube · 3:16 ### Alignment Balancing is about the wheel. Alignment is about the angle of the wheel on the car. Sensors clamp to each wheel and the computer shows camber, caster and toe against the factory specification. More in [balancing vs alignment](https://appointauto.com/guides/tire-balancing-vs-alignment/). ![Wheel alignment sensor clamped to a car wheel on an alignment rack](https://appointauto.com/media/field/alignment-clamp.jpg) An alignment sensor clamped to the wheel on the alignment rack. Photo: [Mike Peel (www.mikepeel.net)](https://commons.wikimedia.org/wiki/File:Wheel_alignment_on_a_Ford_Focus_1.jpg), [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/), Wikimedia Commons [Video: Why Do Cars Need Wheel Alignment?](https://www.youtube.com/watch?v=OzKfG7z2c4U) Hunter Engineering, which makes alignment equipment, explains how a car out of alignment wears tires unevenly, pulls and puts the steering wheel off center. Video: Hunter Engineering · YouTube · 1:20 ### Puncture repair A nail in the tread can usually be repaired if the hole is small and away from the sidewall. A proper repair is done from the inside with the tire off the rim, a patch and a plug together. The rules are in [when a tire can be repaired](https://appointauto.com/guides/tire-puncture-repair-rules/). ![Nail lying next to a car tire on the road](https://appointauto.com/media/field/tire-nail.jpg) Nails and screws are the most common reason for a slow leak. Photo: [Etan J. Tal](https://commons.wikimedia.org/wiki/File:TireNail1-2.jpg), [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/), Wikimedia Commons [Video: Tire Safety Starts with Proper Tire Repair](https://www.youtube.com/watch?v=mdTAalpkSLM) The Tire Industry Association puts a camera inside a tire to show what a nail does to the inner liner, and why a proper repair is made from inside the tire. Video: Tire Industry Association · YouTube · 4:41 ### Checking tread and age The raised bars in the grooves are tread wear indicators. When the tread is level with them, the tire is at 2/32 of an inch and must be replaced. The four-digit DOT date code on the sidewall tells you the week and year the tire was made. ![Car tire tread with a raised tread wear indicator bar between the grooves](https://appointauto.com/media/field/tread-wear-indicator.jpg) A tread wear indicator bar. When the tread is level with it, the tire is worn out. Photo: [Quallyptus](https://commons.wikimedia.org/wiki/File:Autoreifen_mit_Verschlei%C3%9Fanzeige.JPG), [CC0](https://creativecommons.org/publicdomain/zero/1.0/), Wikimedia Commons ![Tire sidewall with the DOT code, plant code, size code and four-digit date code labelled](https://appointauto.com/media/field/dot-date-code.jpg) The DOT code on the sidewall. The last four digits are the week and year the tire was made. Photo: [Chrismeraz](https://commons.wikimedia.org/wiki/File:DOT_tire_code.jpg), [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/), Wikimedia Commons [Video: How to Measure Tire Tread Depth](https://www.youtube.com/watch?v=Khszy8gTEpI) Michelin shows the penny test for checking how much tread is left. Video: Michelin USA · YouTube · 0:42 ## Part 3: winter driving in California Mountain highways to Tahoe, Mammoth and Big Bear can have chain controls. Carry chains that fit your tire size and practice once at home. See [California chain controls](https://appointauto.com/guides/california-chain-controls-winter-tires/). ![Snow chains fitted on the front tire of a car in snow](https://appointauto.com/media/field/snow-chains.jpg) Snow chains fitted on a front tire. Photo: [Domitori (English Wikipedia)](https://commons.wikimedia.org/wiki/File:Snow_Chain_Honda.jpg), [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/), Wikimedia Commons [Video: Caltrans/CHP Chains Q&A](https://www.youtube.com/watch?v=CyARakDD41s) A Caltrans superintendent and a CHP officer answer common questions about chain controls and chain checks. Video: Caltrans District 2 · YouTube · 3:52 ## About these photos and videos All photos are from Wikimedia Commons and are public domain or Creative Commons licensed; the author and license are under each picture. Videos play from their creators’ YouTube channels and load only when you press play. The 1975 smog photos come from the U.S. EPA DOCUMERICA project at the National Archives. ## Find a shop - [Smog check in Los Angeles](https://appointauto.com/smog-check/los-angeles/) — 3 listings - [Smog check in Oakland](https://appointauto.com/smog-check/oakland/) — 3 listings - [Smog check in Sacramento](https://appointauto.com/smog-check/sacramento/) — 3 listings - [Smog check in San Francisco](https://appointauto.com/smog-check/san-francisco/) — 3 listings - [Smog check in Sunnyvale](https://appointauto.com/smog-check/sunnyvale/) — 3 listings - [Smog check in Anaheim](https://appointauto.com/smog-check/anaheim/) — 2 listings - [Smog check in San Jose](https://appointauto.com/smog-check/san-jose/) — 2 listings - [Smog check in Santa Clara](https://appointauto.com/smog-check/santa-clara/) — 1 listing - [Tire shops in Sacramento](https://appointauto.com/tire-shops/sacramento/) — 4 listings - [Tire shops in Anaheim](https://appointauto.com/tire-shops/anaheim/) — 3 listings - [Tire shops in Los Angeles](https://appointauto.com/tire-shops/los-angeles/) — 3 listings - [Tire shops in Oakland](https://appointauto.com/tire-shops/oakland/) — 3 listings - [Tire shops in San Diego](https://appointauto.com/tire-shops/san-diego/) — 3 listings - [Tire shops in San Francisco](https://appointauto.com/tire-shops/san-francisco/) — 3 listings - [Tire shops in San Jose](https://appointauto.com/tire-shops/san-jose/) — 3 listings - [Tire shops in Sunnyvale](https://appointauto.com/tire-shops/sunnyvale/) — 3 listings - [Tire shops in Santa Clara](https://appointauto.com/tire-shops/santa-clara/) — 1 listing ## Frequently asked questions ### How long does a smog check take? For most cars from 2000 or newer, the test itself takes about 15 to 30 minutes. Older cars that need a tailpipe test take longer. Book a time or call ahead so you do not wait behind other cars. ### Can I watch while the shop works on my car? Many smog stations let you wait where you can see the lane. Tire shops usually keep customers out of the bay for safety, but most will show you a worn part or a puncture if you ask. ### Why are some of the smog photos from 1975? They come from the U.S. EPA DOCUMERICA project, which photographed one of the first emission inspection stations. They are in the public domain. Today’s California test uses the same idea, but newer cars are tested by plugging into their computer instead of only measuring the exhaust. ### Who made these photos and videos? The photos are from Wikimedia Commons and each one is credited with its author and license under the picture. The videos play from the YouTube channels of the Bureau of Automotive Repair, Caltrans, tire makers, the Tire Industry Association and Consumer Reports. AppointAuto is not affiliated with them. ## Related guides - [How to Pass a California Smog Check: 10 Checks Before You Go](https://appointauto.com/guides/how-to-pass-smog-check/) — A practical pre-test checklist: check engine light, readiness monitors, gas cap, oil change, warm engine and the mistakes that make good cars fail. - [Tire Balancing vs Wheel Alignment: What Is the Difference?](https://appointauto.com/guides/tire-balancing-vs-alignment/) — Balancing fixes vibration by evening out weight around the wheel; alignment fixes pulling and uneven wear by correcting wheel angles. How to tell which one you need. - [Can My Tire Be Repaired? Puncture Repair Rules Explained](https://appointauto.com/guides/tire-puncture-repair-rules/) — A puncture is repairable only in the tread and up to 1/4 inch, with a plug-and-patch from inside. Sidewall or shoulder damage means a new tire. [Find a shop near you](https://appointauto.com/) --- Source: https://appointauto.com/guides/smog-and-tire-shop-photo-tour/ · Last updated 2026-10-25. Station details are compiled from public listings and can change; call the shop to confirm hours and prices before you go.