In the garage blow out

[Timothy Keith-Lucas]

With you, pethier. After years of waiting while little compressors did big jobs, I broke down and squeezed a real compressor into my over crowded shop. Damned good investment. It helps having a wife who restores Ford Model Ts. 

 

MV8: Thanks as usual. Tire Rack discourages using torque rods, I suppose because they are not exactly precise. I'll use a good torque wrench, but I don't do many tires. For a garage staffed by Florida Good Ol' Boys (Love 'em, but the headlines are a constant source of dismay), torque rods seem to me the most practical solution. Even if the boss just put an 85 ft lb rod on the air wrench, and all their vehicles got that, it would be better than everyone getting 200+ ft lbs. 

[IamScotticus]

On the ground, Front camber can preload the lower nuts by 10 lbs ft.   At least rotate the wheels 180° to even out the torque. Or tighten nutz off the ground.  I use a wedge under the fronts.  Parking brake holds the rears.

 

Gorilla splined anti theft nuts in use.

[MV8]

4 hours ago, pethier said:

 After an oil change, I went to pick up my trailer.  In a bit of flukey wind, the rig with empty trailer was all over the road.  I stopped to check the pressures:  36 PSI!  They sent me a survey email and I sent back an email that they had better not deflate my tires if they wanted me to send in a favorable survey.  They have promised to not do this again.  Do you know how long it takes to get tires this big from 36 to 80 with a domestic-size compressor?

You were not towing and they set the pressure accordingly. If you were towing an empty trailer, 80 psi is not correct either. "under-inflated" does not mean anything less than the max load pressure.

[theDreamer]

Same issue with over torqued nuts but different results. My oldest grandson is now the owner of my 2018 BRZ tS. I’ve always changed or rotated the tires with a breaker bar and a torque wrench. The car had to have a safety inspection done when transferring it into his name. Come the late fall he came over to our house to change over to the winter tires. We had a devil of a time getting three of the wheels off and the forth we ended up going to a local Canadian Tire store to have them do it.

Next two times (following spring and fall) he broke two studs. They just twisted off like old rubber. He was going to get all the studs replaced with some special treated studs the drift guys use but I’m not he has done that yet.

This seems to be a failing with many newer cars, not just Subaru.

[panamericano]

Bit off:

Some wheels sailing down the road are not a result of torque error.  Had an interesting spate of bus wheels leaving.  One across a busy "business route" and one on I.H.35 that was found 1.5 miles down the road.  Lots of trouble to track down the cause.  They were mounted with a proper torque wrench (XXL).  Turned out the painted steel wheels were not oven cured properly.  After a bit of wear, the paint gave a bit and off goes the lug nut. 

I wonder how easy a similar thing could occur with old alloy wheels or cheap bad metal studs.  

Edited October 15 by panamericano

[MV8]

I have air tools but very rarely use them for anything. I use a large four-way lug wrench (14 inch I think and a two-armed arrangement which has much greater leverage). I have folding four ways in the cars appropriate to the lugs (sae or metric). I've only needed a breaker and 3/4 sockets on commercial vehicles.

[speedwagon]

Once over torqued a bolt or stud becomes a time bomb waiting to blow! And going down the highway it could easily kill several people. NEVER re-use a bolt or stud or nut that has been over torqued!! 

[Timothy Keith-Lucas]

With you, Speedwagon.

 

I seem to have hit a nerve here - we've all had experiences with over-torqued lug nuts. Anyone got a link to a source of replacement studs?

 

I was in my seventies before I understood the principle here - that you torque nuts (not just lugs) into their elastic range so that the bolt and nut form a spring clamp holding the two parts together. When you torque into the plastic range, you actually lose clamping pressure, and as Speedwagon says, you've got a time bomb on your hands. Some bolts (particularly aircraft) are torqued and then tightened 90 degrees, for maximum holding power, but they are one use only. Go over the 90 degrees and you have to start over with a new very expensive bolt.

[MV8]

I have catalogs I use to ID and cross reference wheel studs and nuts. There are often a variety to suit or upgrade an application. A stud should be removed to measure with a dial caliper to ID a replacement. Provide thread pitch, overall length, unthreaded shoulder length, and knurl OD.

[IamScotticus]

Stupid thing I did before I knew better...I coated my studs with WD40.  Just thought it was a good idea.

I since learned it wasn't a good Idea.  Studs stay dry.  Clean them up with a wire brush if they get ugly, but no added preservatives.  Clean and dry.  Luckily I didn't have to learn this the hard way.  

[MV8]

I prefer to lubricate all hardware for some corrosion protection and antisieze but the torque spec complicates things.

 

https://www.engineeringtoolbox.com/torque-lubrication-effects-d_1693.html

 

When a bolt is lubricated - less torque is required to achieve bolt axial load or tension. Reduction of torques for lubricated vs. dry bolts are indicated in the table below.

Lubricated Bolts - Reduced Torque

Lubricant	Torque Reduction (%)
Graphite	50 - 55
White Grease	35 - 45
SAE 30 oil	35 - 45
SAE 40 oil	30 - 40
No lube	0

Example - Reduction of Torque when Bolt is Lubricated

The maximum tightening torque for a slightly lubricated 1" Grade 5 coarse bolt is 483 lb_f ft. Dry bolt torque is approximately 30% higher - or 628 lb_f ft.

T_dry = (483 lb_f ft) (1 + (30%) / (100%))

   = 628 lb_f ft

If the bolt is lubricated with SAE 30 oil - the torque compared to a dry bolt is reduced with approximately 40%.

T_SAE30 = (628 lb_f ft) (1 - (40%) / (100%))

   = 377 lb_f ft

Note that if torque specified for a dry or slightly oiled bolt torque is applied to a lubricated bolt  - the bolt may overload and break.

 

Edited October 18 by MV8

[speedwagon]

MV8 your level of education never ceases to amaze me.  For my use since I either use light oil. anti seize or lock-tite, i will just use 60% and be so much better of than before, as to be amazing. And thank you very much for this and the many previous surprising pointers that you have given us.   john     Although through the years of assembling engines including VW and Corvair air cooled (many under high intake pressure) I have never broke a head bolt or stud nor had a early blown head gasket using my routine of tightening slowly in 5-10 lb increments.  once again thank you!

[pethier]

On 10/15/2025 at 2:12 PM, MV8 said:

You were not towing and they set the pressure accordingly. If you were towing an empty trailer, 80 psi is not correct either. "under-inflated" does not mean anything less than the max load pressure.

I did tell them I was leaving for a long trip and would be towing.

 

When one brings a vehicle to this Ford dealer for service (whether one goes home or hangs in the customer lounge) one gets texts about every little detail.  I typically get a half-dozen or so of these messages every time.  Not a peep about tire pressure.  In this context I would expect nothing less than a text telling me they thought the tire pressures were high.

 

I do find it interesting that my 496-cubic-inch Suburban had posted on the door frame from Chevrolet that the tire pressures were to be 50 PSI in front and 80 PSI in back.

The F-150 says 35 PSI on the door frame.  The published load and towing weights for this F-150 with the towing package with which it was delivered new are similar to those of the Suburban.

 

I understand your position that tires give their maximum traction when inflated to an ideal pressure taking into account weight on the tire patch, tire size, tire structure, wheel size, dynamic camber at expected cornering forces, and other things too numerous to mention.  The traction of the Load Range E tires on this F-150 is perfectly-sufficient for the use of the vehicle at 80 PSI.  Is 80 PSI ideal for traction and wear patterns?  No.  Is it sufficient for preventing tire-killing heat?  Yes.

 

I ran the Michelin LT all-weather tires on the Suburban at 50/80 year-around, towing and deadheading.  I rotated them occasionally.   I eventually wore out a set.  They were very-evenly worn when I replaced them with another set of the same.  The truck towed straight and true without benefit of any sway-control devices. (The motorhome requires a friction snubber).

 

I could not seem to get the same Michelin tire for the F-150. New 4WD F-150 trucks are supplied with "terrain" tires.  I have not looked at the tires on new trucks at the dealership to see the load range.  My truck was used, and the dealer (sister-dealer to the one closer to my house where I get service) had replaced the tires with summer-tread car tires with a load rating and maximum PSI rating I consider insufficient.  These Cooper tires were described as the most "highway friendly" of all the Load Range E tires offered me.  I tried running them at 50/80.  There was a lot of sway while towing.  I put on the snubber and it knocked down the terrifying sway, but the snubber has a little play in the couplings which allows annoying amounts of sway.  Raising the front pressure to 80 helped. 

 

The F-150 has a longer wheelbase and a shorter rear overhang than the Suburban, so is should have less sway, not more.  The only significant variable appears to be tread squirm.  Maybe next spring I will try to figure out how to get Michelin all-weather tires on this truck.  I really don't want two sets of wheels because they are so large to store.