Block Wheels

Wheel blocks, also known as “chocks,” are an overlooked safety precaution in both the home garage and the maintenance bay. When positioned against the wheels, they prevent vehicles from rolling and causing potentially fatal accidents. Chocks should always be employed anytime your vehicle is resting on a jack or a slope, or if you are working underneath. To use them correctly, first make sure you choose the right chocks for the surface you're on. Put the vehicle in park and apply the emergency brake. Then, wedge the angled chocks beneath the tires on both sides to keep the vehicle from budging.


Positioning Chocks Correctly

  1. Wedge the angled edge of the chock beneath the wheel. Set the chock down so that it's resting flat on one side. Scoot the narrow end under the tire in whichever direction you want to prevent the vehicle from moving. Give the backside of the block a few taps, or back the vehicle up slowly until you feel it seat securely.[1]
    • Check to make sure that the chocks are centered on the tires and that the entire front end sits snug against them.
    • Don't adjust the wheel blocks any further once you get them where they need to be.
  2. Repeat on the opposite wheel. Since the vehicle’s axle causes both wheels to turn together, it won’t be enough to simply chock one of them. Set up a second block just as you did the first, making sure they’re aligned and on the same side of the tires. In the event that the emergency brake fails, the chocks will act together to catch and immobilize your vehicle.[2]
    • Every action you complete on one side of the vehicle should be mirrored on the other.
    • If the front end of the car is lifted, for instance, there should be a chock behind each of the rear wheels.
  3. Block all wheels that are touching the ground. As long as a wheel remains in contact with the work surface, there is some danger of rolling. Generally, it’s safest to just use chocks on every wheel that’s still down.
    • When you’re parked on a hillside or a patch of irregular terrain, be prepared to use a chock for all four wheels.

Choosing the Right Chocks

  1. Use chocks that are an appropriate size for your vehicle. Not all chocks are created equal. As a general rule, you’ll want to shop around for blocks that are at least one quarter of the total height of your vehicle’s tires. The greater the point of contact with the tire, the better able the chocks will be to keep the vehicle from budging.[3]
    • For a set of 20” (51cm) tires, you should use chocks that are a minimum of 5” (13cm) tall.
    • If the blocks are too short, a runaway vehicle may simply force them aside or roll right over them.
  2. Pick the right material for your work surface. Before you set up your wheel blocks, consider what type of surface your car is parked on. For instance, textured plastic blocks may work well on gravel or clay, but they’ll be too smooth to offer much traction on paved surfaces. Similarly, rubber-coated metal chocks that provide reliable traction elsewhere might be at risk of slipping when used on wet grass.
    • Chocks are manufactured in several different materials. There are wooden chocks, metal chocks, and even hard plastic chocks.[4]
    • It may be wise to invest in a few different types to ensure that you’ll always be prepared in the event of an emergency.
  3. Avoid using improvised wheel blocks. Mechanics have sometimes been known to repurpose makeshift objects like bricks or 2x4s in a pinch. This isn’t a good idea. Don’t take chances with your own safety—only manufactured chocks that have been approved for use on vehicles the make and size of your own should trusted for blocking.
    • Despite seeming solid, bricks, cinder blocks, and other composite materials are easily crushed when put under enough pressure. Likewise, wooden boards are typically smooth and lightweight, which makes them prone to slipping.[5]

Using Chocks Safely

  1. Park your vehicle and engage the emergency brake. Move the gear shift into the “park” position and turn off the engine. Then, apply the emergency brake by pulling up sharply on the handle. The emergency brake is your vehicle’s first line of defense against rolling while it’s not in operation.[6]
    • On some models (particularly those with electronic safety features), a separate button or pedal may have to be pressed in order to engage the emergency brake.[7]
    • It’s important to note that the emergency brake is most often linked to the back wheels, which means it won’t be of any use when the rear of the vehicle is off the ground.
  2. Always set down chocks before performing any maintenance. Don’t do anything until your vehicle is parked and blocked—you want to be certain that it’s not going anywhere. Then and only then should you proceed to pop the hood, fit a spare, or take a look underneath.
    • It’s especially important to put chocks to use when you find yourself stopped on dirt, mud, grass, gravel, or wet pavement.
    • Safety is always the first priority, even for quick fixes and routine inspections.
  3. Keep a set of chocks in your vehicle. That way, you’ll have additional safety measures in place whenever you experience car trouble while you’re away from your home or garage. You shouldn’t have to worry about them taking up too much space—most wheel blocks are small enough to stash in the trunk or under the seats.
    • Break out your chocks anytime you have to change a tire, drain your oil, or prop your vehicle up on a jack for any reason.
  4. Replace chocks when they begin to wear out. Over time, the constant pressure and friction created by supporting the weight of the vehicle can take their toll. If your chocks are beginning to show signs of deterioration, such as scraping, denting, or excessive rubbing, it may be time to trade them in for a newer, more dependable set.[8]
    • The chocks might look okay structurally, but if they lose too much traction, they may not be able to hold the vehicle.
    • Chocks are sold in pairs and tend to be relatively inexpensive. In most places, you can purchase them for as little as $10-20 USD.


  • In addition to cars and trucks, chocks should always be used when servicing or repairing motorcycles, ATVS, boats, tractor trailers, and even aircraft.
  • You can purchase a set of chocks at any major auto parts store or car dealership, or in the automotive department of superstores like Walmart.
  • Steel chocks with rubberized tread make great all-purpose blocks for a wide range of work surfaces.


  • While wheel blocks are an indispensable safety precaution, they’re not entirely foolproof. Try to minimize the amount of time you spend under or near a blocked car as much as possible to avoid any unfortunate mishaps.


You may like