Anonymous
Anonymous asked in Cars & TransportationMaintenance & Repairs · 5 months ago

When tightening lug nuts, after changing a tire... (2 questions)?

I have always heard you tighten the lug nuts by hand while the car is in the air, slightly lower the car so that the tire is resting on the ground (though not the full weight of the car) and then use the iron to fully tighten them.

Why not fully tighten in the air?

Why not fully tighten after completely lowering the car?

Update:

I would like to place emphasis on the second question:

Why not fully tighten after completely lowering the car?

9 Answers

Relevance
  • 5 months ago
    Favorite Answer

    Sufficient force to properly tighten the lug nuts will SPIN the tire.

    If you put the weight of the vehicle on the tire before partially tightening the lug nuts, you you won't be able to properly set the wheel.

    That said, you actually should have the full weight of the vehicle on the wheel when torquing the lug nuts.

    • Cap'n. America
      Lv 4
      5 months agoReport

      Not if in gear and other wheel on ground or parking brake set or passenger holds with brake.

  • xxxxxxxxxxxxxxxxxxx

  • 5 months ago

    Yes you should SNUG up the lug nuts by hand and the TIRE IRON while the tire is off the ground. Fully tighten the lug nuts when the wheel is on the ground.

    It's impossible to fully torque-up the lug nuts with the wheel in the air. The wheel would spin without it touching the ground.

  • Erik
    Lv 7
    5 months ago

    As others have said, if you try to tighten them while the car is on a jack, you could knock it off, which would be bad. Of course, if it's on a lift, go nuts. I've always just finger tightened them while on the jack, then lowered it all the way and made them as tight as possible. That's just me though.

  • How do you think about the answers? You can sign in to vote the answer.
  • 5 months ago

    When a car is on the RAC in the air they use the air gun to tighten it all the way. The reason you wouldn't want to use a tire iron while it's in the air is 4 reasons of safety. You might rotate the rack and cause the car to hit something or fall off. To use the power wrench all the time tighten it all the way before they set it down

    • JetDoc
      Lv 7
      5 months agoReport

      AFTER spinning the lug nuts on with an air impact gun, they MUST be tightened with a torque wrench to insure they are at the proper torque setting. Failure to do that COULD result in a warped brake rotor OR a loose wheel.

  • Anonymous
    5 months ago

    Because the wheel may be able to spin unless the brake is on. I use this to advantage to whip a lug not tight. But the final tightening on the ground. U don't want U R wheel to fall off.

  • 5 months ago

    I see two issues. 1. you will often just spin the wheel if you try and torque it. 2. If you start yanking on wheels with the car in the air, you might knock it off of a jack stand and cause some additional problems.

  • Jason
    Lv 7
    5 months ago

    You can tighten them while it's in the air but you either need to apply the parking brake or have someone inside the car to apply the brake otherwise the wheel will just spin.

  • 5 months ago

    I have indeed tightened lug nuts fully while the car was in the air. I use an impact wrench with a torque stick. The torque stick is to keep from overtightening. However it is better to do it with the car on the ground. I also want to emphasize that getting the nuts to the proper torque is very important. If you just "go gorilla" on them, you may warp the brake rotors and put too much stress on the lug stud, which could then fail. You might not be able to get them off if you have a flat. Fail to tighten them enough and then they come loose. A good torque wrench is a mechanic's best friend.

    • Erik
      Lv 7
      5 months agoReport

      So you're worried that someone will be so ******* strong, they will damage the lug nuts by over-tightening?

Still have questions? Get your answers by asking now.