# What size nut goes onto a typical US passenger tire Schrader valve?

What size nut goes onto a typical US passenger tire Schrader valve?
To insert the tire valve, I know there is a ridiculously cheap cross-type valve tool where you thread it on the outside of the tire valve to pull the tire valve through the hole in the wheel rim, but for emergency use I just want to stock a few nuts that I can thread on the outside of a new valve to use as a ledge to pull the tire valve through the hole as shown here:
https://d3vl3jxeh4ou3u.cloudfront.net/10%20-%20How%20to%20Install%20Valve%20Stems%20on%20Tires%20-%20Picture%20of%20person%20pulling%20valve%20stem%20into%20position%20from%20inside%20of%20tire%2C%20using%20needle%20nose%20pliers.jpg
Looking for what nuts to purchase, the Wikipedia for Schrader valves says the typical passenger brass & rubber tubeless tire pop-in Schrader valve has OD threads of:
*TR 418, 0.453 in (11.5 mm) rim hole diam. 2 in (51 mm) long* [*] Metric: 7.7 mm OD, thread root diameter is 6.9 mm ? 0.794 mm pitch [*] Imperial: 0.305 in OD, thread root diameter 0.271 in ? 32 tpi (threads per inch; thread density)
Assuming "Imperial" means "USA", that would mean I need a 32 TPI nut somewhere between 0.271 inches and 0.305 inches in iD, but that doesn't seem to be a standard size for a USA nut. http://www.engineeringtoolbox.com/inches-decimal-equivalents-d_471.html
Even if I look deeper into the granularity, it still seems an odd size:
http://www.liming.org/InMoov/pics/decimalchart.jpg
So I simply ask you if you have experence with this problem.
What size nut goes onto a typical US passenger tire Schrader valve?
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On 12/6/2016 10:07 AM, Leon Schneider wrote:

Can't you use a metal valve cap? You need a cap anyway, so it's always there in an emergency.
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says...

There is no 'standard' nut to be found that will fit the tire valve.
The valve has been the same odd ball value for all tires US and others from about the time of the first tires.
Standard automotive (car) Schrader valve dimension is
7.7 mm OD
32 tpi, or 0.794 mm pitch
Minor diameter is 6.9
Thread designation is .305-32 or 7.7-32
Nice mix of inches and millimetres!
If you want a nut, you are probably going to have to make your own or have it made for you.
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Leon Schneider posted for all of us...

You aren't going to able to do with out the tool. You may have a TPMS stem.
If you insist, I would get some extended metal valve caps and have at them as you wish.
Remember the valve cap has a very large job of keeping the air in the tire as schrader valves are dodgy.
--
Tekkie

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Tekkie? wrote on Tue, 6 Dec 2016 15:45:19 -0500:

It's the old style (1995) valve stem so there is no TPMS. Sorry for not mentioning this in the OP.
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Leon Schneider wrote:

It doesn't exist commercially but if you really want to go that way Schrader thread taps are available (try ebay) so you could drill an existing nut to the tapping diameter and make your own.
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John H

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@hotmail.com says...

4-way valve stem tools cost less than \$2. It amazes me why some people want to reinvent some things.
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RonNNN

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RonNNN wrote on Tue, 6 Dec 2016 15:39:37 -0600:

Assuming the tire is off the rim, can I both remove an old valve and replace it with a new valve using that cheap 4-way tool?
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Leon Schneider wrote:

Easily. To remove the old one you just cut the inside section off. That keeps you from trying to reuse an old stem. Next take the new stem, coat it with either tire lube or some very soapy water and put it through the hole, then pull with the 4 way while moving your hand in a circle (not turning the valve). It will pull right into place.
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Steve W.

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Steve W. wrote on Wed, 07 Dec 2016 04:08:41 -0500:

Thank you for that advice as it's not obvious that the tiny \$2 four-way tool is good enough considering my searches found a bunch of tools for removing and replacing automotive tubeless tire valve stems from a. Cable pullers b. Grooved hinged levers c. Hook-and-funnel tools (these work without breaking the bead though) d. And the inexpensive 4-way tool
I have the rubber and brass style but is it different for the style that has metal nuts or similar?
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says...

Yes. And as you've posted the video's you now know you can change the stem without removing the tire.
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RonNNN

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RonNNN wrote on Wed, 7 Dec 2016 06:35:52 -0600:

Thanks for confirming that the cheap tool works just fine for my purpose, where the tire is already off the rim.
The one hook-and-funnel tool works with the tire on the rim, whereas the rest of the tools I found work with the bead broken at least well enough to get your hand in there.
Since I've seen in the videos people replacing the valve by breaking the bead while the tire is still on the car, one guy had a neat trick where he tied a long string to a drywall screw and before he cut the old valve stem in half, he screwed the screw into the backside (inside the tire) of the rubber valve stem.
That way, if the inside cut-off rubber part fell, he could retrieve it easily. For him, this was important because he was breaking the bead with the wheel still mounted to the vehicle.
For me, the tire will always be off the rim so I don't need that string-and-screw trick, but it's nice to know about in a pinch.
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On Wed, 7 Dec 2016 05:35:41 -0000 (UTC), Leon Schneider

Remove with a utility knife, install with the tool. Soap the stem first.
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snipped-for-privacy@snyder.on.ca wrote on Wed, 07 Dec 2016 08:02:40 -0500:

Thanks for confirming that the cheap tool works just fine.
As you probably know, experience in choosing tools is everything because ometimes you don't want the cheap tool, and sometimes you do.
It all depends, usually, on three basic things for all tools: 1. Use the cheap tool if it does the job well enough to do it right 2. Buy the expensive "finesse" tools if you do it a lot 3. The smaller and easier stored the tool, the better (for storage reasons)
This 4-way cheap ubiquitous tool meets the standard tool's #1 and #3 criteria, and since I'm not doing the job a lot, I don't need to meet the #2 criterion for "elegant" tools.
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Leon Schneider wrote:

If you're going to be doing tens, hundreds, or thousands of wheels then get the best tool that you can afford. Usually that means the most expensive.
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Paul in Houston TX wrote on Wed, 07 Dec 2016 12:11:05 -0600:

I appreciate the insight but you hit a sore point with me so please don't take my diatribe below personally - but I've heard too many people say what you just said, which I think is the wrong approach entirely.
You don't approach a tool from a cost perspective; you approach a tool from the quality of results perspective.
I realize you said "usually", so, I agree that you're already on board, when I say that choosing tool-quality by cost is entirely the wrong logic, but the other half of what you said is the correct logic, which is to use the best tool if you need it.
Whether or not it is expensive is completly meaningless (most people simply *assume* expensive stuff is better becuase it's a simple number and they can handle numbers but they can't handle myriad technical details when comparing two different tools).
For example, a 100K dollar alignment system may not be any more accurate than a \$500 alignment system, but it does stuff that the shop needs, e.g., it allows dumber people to operate it and it allows hands-free measurements and it allows cars to be easily ramped on and off and it allows printing of the results, etc.
None of that has any bearing on the quality of the results and all of that raises the expense of the machine such that the local morons down the street think you have to buy an alignment tool for 100K dollars just to get a "good" alignment.
You can get a good alignment for probably 100 dollars in tools, and certainly for 500 dollars in tools; but it won't have all that time-saving stuff (where for a mechanic, time is money).
In contrast to your point, it may very well be that a \$100 cellphone gets you as good an alignment as a \$100K alignment tool.
The only thing that matters is the quality of the results. The cost of the tool isn't a factor in the quality of the results.
To the point, I'm not positive yet because I haven't done it, but I would bet that the quality of results from using a nail inside the tire valve when seating it is as good as the quality of results from using that \$25 grooved swivel-head lever tool just as the quality of results when removing the valve with a utility knife is probably as good as the quality of results when using that fancy tool.
PS: I didn't aim this *at* you, but at the team becuase too many people use "cost" of things as a "quality" measurement - and it's never the case. People just use "cost" because they don't understand quality but they understand numbers such as numbers of dollars. But it's the wrong way of looking at tools (it's a factor though).
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On Wed, 7 Dec 2016 21:35:23 -0000 (UTC), Leon Schneider

I have long held to the position "never buy the cheapest or the most expensive, because you will be overpaying for either one"
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On Wed, 7 Dec 2016 21:35:23 -0000 (UTC), Leon Schneider

There is a cellphone alignment tool? I have done the string and measuring tape thing (and generally been more satisfied with it than I have been by sending it to shops with expensive tools operated by high school kids), but I'd be willing to spend a couple hundred dollars to do a better job. Tell me more! --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Scott Dorsey wrote on 7 Dec 2016 21:06:25 -0500:

There are three jobs almost nobody does at home, all three of which I'd love to learn how to do because they can't be as hard as people think: 1. Paint your car 2. Replace & balance tires 3. Align your suspension
Depending on the car, the suspension issue is twofold: a. You have to *understand* what you're doing b. You have to *measure* what you've got
An alignment, like changing oil, should be done as often as you can do it, but, like changing oil, in reality, alignments are done far less than people say they do them.
Why? Because they're expensive (about \$100 on sale where I live but I know the price varies greatly) and they take effort (an hour minimum but more like three hours from leaving the house to getting back to the house).
The main problem people have with alignment is self made. They *think* they need a tool that costs \$100K.
But that \$100K one-man-operated alignment tool has, just as an example, a \$20K lift and a \$10K laser system and \$30K of software to handle all cars and a \$5,000 printer option, etc.
None of which a home garage mechanic needs. That tool is made for a different purpose - which is to get a huge variety of cars in and out of that shop in no time fast by one guy.
Also, that \$100K tool measures stuff that you can't do anything about, such as tracking and ackerman angles and steering axis inclination, etc.
My sedan only has 3 settable items: a. Front toe b. Rear camber c. Rear toe
That's it. Nothing else is adjustable (although camber plates can be put nio the front struts).
So, from that perspective, home tool only needs to measure toe & camber. Nothing else.
Toe is relatively easy, especially with a helper. So is camber.
Camber is just an angle, and toe is just a distance. Smartphones can measure angles easily.
The only thing a home owner needs are knowledge and jigs.
The lack of knowledge is the *real* reason most homeowners don't do alignment at home, but the lack of jigs slows them down.
For example, you need a jig to measure the midpoint of the tire treads wheel to wheel (or worse, wheel to centerline of the vehicle).
And you need camber plates (yes there are redneck methods) to adjust camber.
But the *real* reason most people don't do a home alignment is that you have to *think* real hard to do it because the measurements are *always* in the wrong units from what you're measuring.
This post is long enough, but that's my story and I'm sticking to it.
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On Thu, 8 Dec 2016 03:03:55 -0000 (UTC), Leon Schneider

Trust me, painting your car is a lot harder than it looks - particularly to do a decent job "at home"
Replacing and balancing tires requires either reasonable equipment or a lot of sweat and sometimes blood and tears to go with it. Doing a proper accurate ballance job requires complex equipment.
Alignment is another story - not hard to measure and adjust toe. Not terribly hard to check camber, but measuring caster requires special tools.

Alignments on today's vehicles really only need to be done if the vehicle is damaged. or parts are replaced. They don't "go out of alignment" unless something bends or wears.

And if you cannot measure the caster and camber you don't know if there is anything wrong - but your tires wear and the car pulls to the left or right. You can't tell if the car is tracking properly or if it has a bent or twisted uni-body or sub frame. I've had to shift the subframe to balance the canber on many a vehicle - and I've had to grind out mounting holes to tweak and shift parts to optimize alignment on many vehicles. I've had to replace struts and spindles to get alignment back into spec after someone kissed a curb or bounced through a pothole - or after colission repairs that were not done properly - very often on vehicles someone had recently purchased - not knowing it had been previously damaged.

And not always terribly accurately - and you still need to know the car is sitting level to start with -

What do you need that for? The inner edge of the rim or the outer edge of the rim works just as well, if not better than the "center of the tread" and is how real alignment equipment works - and it checks to make sure the rim is "true" and compensates if it is not - - -

Only less than 1 in 1000 people is "capable" of doing a proper alignment without proper equipment - and only about 1 in 4 (being charitable here) mechanics can do it WITH the proper equipment.
That's my story - and I'm sticking to IT. As a former mechanic and former service manager and shop foreman who has had a few very good front end men, and a lot more who would starve to death doing it flat rate and choke on their come-backs.
You are obviously a lot less fussy than the average customer.
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