What is the correct fastening torque for a lug bolt?

[visedog]

The service manuals of most cars and SUVs specify tire lug bolt fastening torque in the range 80 - 100 ft lb, yet I see many people over tightening the bolts to more than 300 ft -lb with air impact wrenches. Isn't this likely to stretch the bolts and ruin them over time?

 

[Blk88GT]

Yes. Add a little corrosion and it also makes flats a pain to change on the side of the road.

 

[LX-Markham]

Question:

What is the correct fastening torque for a lug bolt?

Answer:

The service manuals of most cars and SUVs specify tire lug bolt fastening torque in the range 80 - 100 ft lb

people over tightening the bolts to more than 300 ft -lb with air impact wrenches. Isn't this likely to stretch the bolts and ruin them over time?

Yes.

 

[North Run Grader]

The owners manual will tell you. My Wrangler is 95 ft/lbs, my personal Sierra is 125, and work F150 is 150. I use the lowest setting on my impact and torque wrench to final torque. I haven't let anyone else install my wheels unless I get to supervise, since I sheared off 2 lug nuts changing a flat tire on a muddy road. If I wouldn't have had a 24" flex handle I wouldn't have been able to change my own tire.

 

[isb cornbinder]

How do you know, for sure, the bolts are being tightened to over 300#'? Using a dial torque wrench to get a reading while loosening the bolts will not be accurate.
I/we have been the victim of a tire shop jockey over tightening the bolts on my wife's Mercedes. The bolts were to tight so the Auto club towed the Mercedes back to the offending tire shop.

 

[jonesg]

The service manuals of most cars and SUVs specify tire lug bolt fastening torque in the range 80 - 100 ft lb, yet I see many people over tightening the bolts to more than 300 ft -lb with air impact wrenches. Isn't this likely to stretch the bolts and ruin them over time?

After the tire place installed 2 new tires we had to use a pipe over the tire iron to get the lugnuts off, it took 2 of us and the nuts fought every inch, coming off with a squeak noise.

I noticed some threads were pulled and had to replace several lugs, cost me $36 plus some new nuts too. It adds up.

 

[visedog]

How do you know, for sure, the bolts are being tightened to over 300#'? Using a dial torque wrench to get a reading while loosening the bolts will not be accurate.

Whenever I get my cars back from service or get new tires, I always have to use more than 300 ft-lb to get the lugs loose. I have a corded wrench rated at 115 ft-lb max and is a good indication that the bolts have been over tightened if it can't get them loosened.

 

[garagelogician]

I always torque to factory spec with a torque wrench. I do most of my own wrenching, but whenever I take my car in for new tires (or other work where they remove the wheels) I always loosen the lugs and re-torque to spec.

 

[joe_padavano]

You will be hard pressed to reach over 300 ft-lb with a 1/2" drive impact gun.

In any case, READ the factory service manual. Every car has a different torque spec based on wheel stud size, wheel material, and lug style (taper seat or shank). As others have said, do it right with a torque wrench. There are lots of gorillas posing a "mechanics". I don't let them near my cars.

 

[CJ7VFR]

I always torque to factory spec with a torque wrench. I do most of my own wrenching, but whenever I take my car in for new tires (or other work where they remove the wheels) I always loosen the lugs and re-torque to spec.

I do the same, especially for my wife's car. She knows how to change a tire in the event she gets a flat, and I want to make sure she can remove the tire from the vehicle and change it. There is no way in hell she would be able to remove the lug nuts if I didn't re-torque them after she gets new tires or brakes.

Also, my dad always said that over-torqued lug nuts can warp the rotors. I don't know if this is true or not, but it always sounded good to me.

Jim

 

[nbpt100]

I guess the point is many service shops use their impacts and over torque the lugs or torque them unevenly.

Totally true.
It is a good way to ruin aluminum wheels and it can cause rotors to warp (uneven torquing). Not to mention the problem already mentioned of not being able to remove them with conventional tools.

The torque spec is generally a function of the diameter of the stud. Larger diameters will have a higher torque spec.

I keep a torque wrench in one of my cars so if I need to change a flat I have it ready. I have not gotten around to getting a second one for my other vehicle.

Some shops use what are called torque sticks on their impacts to control the torque I don't get how they are suppose to reliably work......One of my former Auto shop teachers who was also a mechanic at a Ford dealer told me he never trusted them to be reliable.

The tire shops I have frequented in recent years have always torqued the lugs by hand and you can watch them do it.

 

[racerex]

I always torque to factory spec with a torque wrench. I do most of my own wrenching, but whenever I take my car in for new tires (or other work where they remove the wheels) I always loosen the lugs and re-torque to spec.

Same for me also. In addition, I put a light coating of anti-seize on the back side of the rim where it makes contact with the brake rotor hat/center hub. I do not place any anti-seize on the studs and/or the lug nuts. I've never had any problems getting correctly torqued lug nuts off, but I have had problems getting a galled up aluminum rim to free up from the brake rotor hat/center hub. If any galling is present, I hit the mating surface with a wire wheel and re-apply a light coating of anti-seize. I go light to avoid the risk of any anti-seize finding its way onto the braking surface of the rotor.

 

[LS6 Tommy]

"Dog bones" or "torque sticks" are total BS. Don't ever let a shop use them if you see they have them. They are only rated to be "correct" when used with the factory specified impact gun, set to factory specs with factory designated air pressure.

I have had 3 studs broken on my cars over the last few years because of those
"labor savers"...

Tommy

 

[jdsac]

Keep a cheap harbor freight torque wrench in the car. They cost as little as $10 when on sale and are close enough . Don't let the tire guy use the gun for anything but running down the nuts. Hand him the torque wrench and make sure he uses it. Too much trouble? It's your car - brake rotors etc don't like to be overtightened.

 

[ScottsGT]

I had a shop strip out a stud on my old '95 Mustang. Called them up to read them the riot act and they said they would replace it at no charge. Told them no thanks, I've already seen your handy work.
Had to buy the replacement from Ford. NONE of the Dorman, etc. at NAPA or anywhere would fit the hole. Ford's was 1/2 the cost of a Dorman at NAPA.

 

[Eslader]

How do you know, for sure, the bolts are being tightened to over 300#'?

I'm not the OP, but I have an 800ft/lb air wrench, and I had to crank for at least 30 seconds to get the lugs off of a car that had been in for a tire repair. I don't know what the exact torque they put on them was, but I guarantee it was a damn sight more than the spec'd 79ft/lb.

 

[Rickss96]

I always torque to factory spec with a torque wrench. I do most of my own wrenching, but whenever I take my car in for new tires (or other work where they remove the wheels) I always loosen the lugs and re-torque to spec.

I also do the same. Learned the hard way a long time ago when I had a flat in the winter in the mountains at night. Couldn't loosen the lug nuts. Eventually a mechanic-type in a pickup truck stopped to help, he had a breaker bar that got 'em loose. Now I re-torque after my current tire shop does any work even though I know they use a torque wrench. Fool me once, not gonna fool me twice...

 

[ScottsGT]

I watch the guys at Discount Tire walk around the car using a torque wrench. They do it right there.

 

[DC73]

I always torque to factory spec with a torque wrench. I do most of my own wrenching, but whenever I take my car in for new tires (or other work where they remove the wheels) I always loosen the lugs and re-torque to spec.

Same here.

DC

 

[Dr Stan]

I watch the guys at Discount Tire walk around the car using a torque wrench. They do it right there.

Same with RABEN, a regional chain. Started with them right after we moved here and have had nothing but excellent service. Had ball joints replaced on my Dakota and within a week one was already bad as it turned out to be a defective one from the factory. They changed it out W/O question. I've also made use of their road service warranty several times. Again no questions asked, just did the job right by me.

 

[Ole Slewfoot]

the DOT would flay you alive if you only put truck lugs down to 300ft/lb.

 

[bwringer]

I watch the guys at Discount Tire walk around the car using a torque wrench. They do it right there.

Yep. DT does it right.

I believe Costco actually hand-torques as well, and they have two guys physically check and sign off.


I once went to the Tire Rack warehouse in South Bend for a set of new tires. They use absolutely no air tools at all -- everything is done by hand. Hand breaker bar, spinner to install the lugs, and hand tighten with a torque wrench.

 

[johnehr]

It had been years since I had a flat away from home, but it happened to me last month and sure enough, the tire shop had super-torqued the lugs and I hadn't loosened and re-torqued once home. All I had was the vehicle's crappy lug wrench, and ended up putting it on each lug as close to parallel to the ground as possible, and then literally standing/jumping on the wrench to break the lugs free. Got 'em all loose, but good reminder to get back into the habit of re-torquing!

 

[rburke65]

the DOT would flay you alive if you only put truck lugs down to 300ft/lb.

I would think you would first have to define"truck".

 

[visedog]

While a torque wrench helps a lot, it is better to develop a feel for how tightly a lug nut is to be fastened by hand. Mentally calibrate the force you can apply by both hands on the lug wrench that came with the car. It is usually sufficient torque (unless you are built like King Kong). Never use air impact wrenches, or pipe extension on the lug wrench, and never stand/jump on it while tightening.

 

[Ole Slewfoot]

How exactly is that better?

I run them in with my impact and tighten the final 1/8-1/4 turn with a torque wrench. Its very consistent, but I might get more practice than average.

I would think you would first have to define"truck".

The DOT isn't very interested in 110 ft/lb 'trucks'.

 

[mbshop]

Always torque with a torque wrench. Mandatory at my shop. Many specialists recommend retorquing after x amount of driven miles. Never saw the need for that but thought I would bring it up. Always check manufacturers specs for the car you are working on, they are not the same. Also remember to torque in a star fashion.

 

[flat tire]

custom wheels may have different torque values than stock. ask the manufacturer of the wheels for the proper torque

 

[Showkey]

I would think you would first have to define"truck".

In the dictionary there is a picture of the new Ridgeline when you look up the Truck.

 

[Falcon67]

I do about the same as Discount Tire, which is my preferred shop for the daily drivers. I'll pop lugs down with air, then finish with a torque wrench. Only way to do it with race cars for sure. 1/2" studs go 80 ft/lbs, the 5/8" on the dragster go 100. The F350 goes 120 as I recall. The rest go to Discount and I don't care as long as the wheels don't fall off.

 

[KenC]

Believe it or not: the local Walmart has the best practice of any local tire shop. They hand start the nuts, run down just to touch with an impact on lowest setting, torque to spec, drive out to the back lot, drive a couple of figure eights with the vehicle then double check the torque.

I've watched them do this several times. I never expected this attention to spec and detail there!

 

[WhiffySpark]

Believe it or not: the local Walmart has the best practice of any local tire shop. They hand start the nuts, run down just to touch with an impact on lowest setting, torque to spec, drive out to the back lot, drive a couple of figure eights with the vehicle then double check the torque.

I've watched them do this several times. I never expected this attention to spec and detail there!

I use a torque wrench drive it to parking spot then hand torque a couple pounds over

 

[aeopav]

In my opinion, (and this is just my opinion) there is nothing at all wrong with using a torque limiting extension. I use one in my shop all the time. It is a 65 Ft/Lb adapter. After it's use I follow up with my Precision Instruments torque wrench to the manufacturers recommended torque setting. I have never had to back off a single lug nut because the torque stick allowed the impact to over-tighten.

I might add I'm a professional aircraft mechanic with 30 years experience, but I really don't think it takes all that to tighten lug nuts properly.

 

[Weird Tolkienish Figure]

My car says 100 foot pounds. I use a clicking torque wrench.

 

[LS6 Tommy]

In my opinion, (and this is just my opinion) there is nothing at all wrong with using a torque limiting extension. I use one in my shop all the time. It is a 65 Ft/Lb adapter. After it's use I follow up with my Precision Instruments torque wrench to the manufacturers recommended torque setting. I have never had to back off a single lug nut because the torque stick allowed the impact to over-tighten.

I might add I'm a professional aircraft mechanic with 30 years experience, but I really don't think it takes all that to tighten lug nuts properly.

You've never had a problem because the torque stick you're using is well below the rated torque of the vehicle and your not doing what the dealers do. They take the torque stick rated for the vehicle specs, start the nuts and just hammer away.

Torque sticks have been proven many, many times to be completely inacurate. The only way something like that could work is if it had a clutch that released at the desired torque. Once the metal in a torque stick reaches the limits of it's elasticity it's almost the same as a standard extension. They just can't properly limit torque.

Tommy

 

[WhiffySpark]

You've never had a problem because the torque stick you're using is well below the rated torque of the vehicle and your not doing what the dealers do. They take the torque stick rated for the vehicle specs, start the nuts and just hammer away.

Torque sticks have been proven many, many times to be completely inacurate. The only way something like that could work is if it had a clutch that released at the desired torque. Once the metal in a torque stick reaches the limits of it's elasticity it's almost the same as a standard extension. They just can't properly limit torque.

Tommy

Just like everything else, if you use them properly you won't have an issue.

 

[LS6 Tommy]

Just like everything else, if you use them properly you won't have an issue.

That's my point, Whiffy. There is no "proper" way to use them. They're intended to be a replacement for using a torque wrench and they are completely inaccurate when used alone. Here's a quote taken directly from a manufacturer:

"By using our torque sticks, you can increase your shop efficiency and eliminate damage caused by impact wrenches. These premium quality brand new torque sticks are a low cost and efficient way to accurately torque wheel nuts properly. There is nothing to calibrate or maintain! Innovative technology guarantees accuracy every time! No more damaged wheels or studs! No more customer hassles!"

People that use a "low" rated torque stick and then go back and verify with a torque wrench are kidding themselves. A torque wrench doesn't "undo" the overtorqued condition created by the torque stick. It will just click at the preset level regardless of how much higher the lug was actually torqued.

I don't see any labor or monetary savings in using a special $30.00 +/- extension and then torque by hand when anybody with half a brain can turn the force down on their impact gun (or, God forbid, even spin the lugs snug by hand), snug them up and then use the torque wrench.

Tommy

 

[sberry]

I never used a stick but cant really see how they would be good.

 

[WhiffySpark]

That's my point, Whiffy. There is no "proper" way to use them. They're intended to be a replacement for using a torque wrench and they are completely inaccurate when used alone. Here's a quote taken directly from a manufacturer:

"By using our torque sticks, you can increase your shop efficiency and eliminate damage caused by impact wrenches. These premium quality brand new torque sticks are a low cost and efficient way to accurately torque wheel nuts properly. There is nothing to calibrate or maintain! Innovative technology guarantees accuracy every time! No more damaged wheels or studs! No more customer hassles!"

People that use a "low" rated torque stick and then go back and verify with a torque wrench are kidding themselves. A torque wrench doesn't "undo" the overtorqued condition created by the torque stick. It will just click at the preset level regardless of how much higher the lug was actually torqued.

I don't see any labor or monetary savings in using a special $30.00 +/- extension and then torque by hand when anybody with half a brain can turn the force down on their impact gun (or, God forbid, even spin the lugs snug by hand), snug them up and then use the torque wrench.

Tommy

There is a proper way. You should start anything by hand regardless if it's a lug nut or a 6mm dash bolt

The biggest issue is people run them down full throttle and crank each one at the same time. You're supposed to snug them up evenly and then do another round with it impacting. I use my gun full power I don't bother turning it down. I can use a 100 ft lbs stick. Then set a torque wrench to 110 and the nut will move before it clicks.

 

[bwringer]

The theory behind torque sticks is actually fairly sound -- it's just that shops generally have their guns running on shop air 120-175 psi, far above the manufacturer's spec of 90psi, then they let it pound away at the torque stick for a minute or so. Ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga ugga dugga... nope, no one's losing a wheel on my watch!

It's one of those things where you have to pay at least a little bit of attention, so it's completely doomed in the real world...

The Costco near me has their torque wrench calibration stand out on the customer area, with a little sign explaining that they calibrate their torque wrenches daily. I kinda like that.