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I was watching a couple of videos on how to change tires and I keep hearing that it is recommended to loosen the lug nuts while tires are touching the ground.

I followed this advice when I changed the first 3 tires, but then I decided to remove the 4th tire while it is still up air (loosen lug nuts star shaped method with impact wrench) and it looked fine to me (I'm not a mechanic so anything would be OK/fine) .

I was speculating it was because of the manual wrench that you need to have the tire be touching the ground?

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That would be correct. There should be no issue of using the impact with the wheel off the ground. You are exactly right in that the tire should be on the ground when using a breaker bar or tire iron. The reason for this, besides the wheel spinning and you never getting the lug loosened, is because you could torque the car over and cause it to fall off of the jack or jack stand. When on the ground, there is no worry about this. With an impact gun, you aren't applying any torque to the wheel, either. You are applying shock and inertia to the lug to get it to come off. Do not use the impact to tighten the lug nuts, though. It is very easy to over torque them. Use a ratchet and finish up with a torque wrench for accuracy.

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    When I see mechanics use a impact gun that can do well over 600 ft lbs of tightening torque all I can do is shake my head. I was at another garage doing a job and a young kid was doing this. Then he broke out the torque wrench after like it mattered. – Ben Jun 4 '16 at 20:18
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    What you may not have seen from the waiting area was that they were using "Torque Sticks". These are a set of extensions which limit the torque that can be applied. They are color coded for different values. He then may have done a quality check with the torque wrench to verify it. – mikes Jun 4 '16 at 21:27
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    @mikes i was standing right next to him no torque stick and he went around like 5 times. – Ben Jun 4 '16 at 21:35
  • PAULSTER2 thank you so much for this answer I know this post is very old but it helped me out so much. xD – Jason Aug 11 at 2:55
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I agree wholeheartedly with both Ben and Paulster. However, I use a high-power air impact for to tighten, on it's lowest setting, and also have a selection of color "torque stix" with a minimum of three passes (snug, torque, final) while in the air. While not perfect, I think this is a reasonable compromise between my efficiency needs and returning a safe proper job to the customer. The torque stix are not perfect, but neither is a non-calibrated click or beam wrench (which can be abused just as much as any other torquing method). My only real problem with dropping the car on the ground to torque, is I work on a lot of lug-centric old stuff... I'd rather let the lug cone do its centering work in the air.

To loosen, run what you got. Bigger is better in this case. Especially when dealing with VW/Volvo/MB-Sprinter type fasteners that are special cap bolts rather than nuts. These can get horribly corrosion welded to a different-metal wheel. Getting the hub/rotor/wheel holes aligned at the same time is always an adventure. I made some alignment studs on a lathe to simplify this for the cars that use it. And I clean and sparingly use anti-seize, even though I know that's a never-ending debate outside of this question.

So, I would say your focus should be about putting the wheels back on properly, with less regard on how one takes them off.

  • Torque sticks are awesome, but the average user isn't going to have them. Agree that without one, it's sheer lunacy to use an impact to tighten. – Pᴀᴜʟsᴛᴇʀ2 Jun 5 '16 at 1:36
  • Spot on. Just wanted to stress the importance of putting them back on properly... And with lug-centric, it's easy to get into a rhythm with a prybar in between other studs for counterforce, and a click-type 1/2" torque wrench. Along your same argument I'd say most "users" (including me) do not calibrate torque wrenches with any regularity... and further have a classic "two clicks plus 20 degrees to be sure" mentality (NOT me) that leaves (or puts too much) on the table. – SteveRacer Jun 5 '16 at 3:27
  • One of the things which drives me NUTS is when you get something done at the tire shop, the "mechanic" (read: tire changer) torques the wheel nuts using a torque wrench, but will rock the car back and forth while torquing ... you know the torque on these things is anything but correct. I NEVER trust what they do. I go home, loosen all of the lugs and retorque ... no rocking this time. – Pᴀᴜʟsᴛᴇʀ2 Jun 5 '16 at 12:24
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    absolutely. The more is better paradigm does not apply. I'd just like to do it correctly the first time. This is actually quite serious; wheels coming off during driving is never a good thing! By now everyone knows how anal I am... But that doesn't necessarily mean I'm wrong... – SteveRacer Jun 5 '16 at 20:55
  • You and I are cut from the same cloth, my friend! :o) As I always say, though, I used to be anal retentive, now I'm just anal, lol! – Pᴀᴜʟsᴛᴇʀ2 Jun 5 '16 at 21:44

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