How about a torque meter? At work we use them to measure how tight a nut has been done up.
You would not be able to tighten them, but you will know how tight they are done up.
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>>How about a torque meter?
To make a tightened fastener move, you need to overcome static friction, which means that you'll have to apply more torque than the fastener was torqued to to make it move.
The only way to get even close to measuring is to use a tight fitting socket - mark the outside of the socket, and the adjacent part of the wheel - loosen the bolt - slowly tighten the bolt, noting the torque as the marks align, but, before the bolt stops moving.**
** Yes, I'm aware of the paradox - it's a serious limitation, but, this is the best method!
Yes, if the fitters have tightened a bolt which should be 100Nm to only 50, you'll find that by checking, but, if the bolt is originally torqued to 85, 90, 100, 110, 120, 130, etc, etc, then, a torque wrench set to 100Nm, or even a torque meter if you stop at 100Nm won't move the bolt.
A good method to use on higher value fasteners in an industrial setting is to grind the end of the bolt square, and measure the undeformed bolt's length with ultrasound, and repeat during tightening. This sidesteps the notoriously unreliable method of torque tightening, and gives a direct indication of bolt strain, hence bolt preload.
>>At work we use them to measure how tight a nut has been done up.
It doesn't sound like a great method to me - hopefully these aren't critical fasteners.
Edited by Number_Cruncher on 03/05/2009 at 20:19
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Can you put snake oil in tyres?
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I wonder who'll be the genius who comes up with the idea of using CO2 in car tyres as a solution for carbon capture storage !
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The idea of using CO2 in car tyres ..
Good thinking MT. Now let me see - 30 million vehicles, average say 6 tyres each, volume about 20 litres @ 2 bar pressure ...
How far would a car need to travel to fill its tyres with CO2? Not very, I suspect :-)
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Scale up the thinking to a global level and there's a huge CO2 storage capacity potential within car tyres.
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There's a huge CO2 storage capacity potential ..
I don't think there is, Mike. Simplify the question to one car - how far would a typical car travel to fill its tyres (include spare, of course) with its own CO2 ?
Say 150g CO2 emitted per km. 44g CO2 occupies 22.4 litres at NTP, so that = about 75 litres emitted per km, or 25 litres at 2 bar overpressure in the tyre.
Volume of a tyre I guess about 20 litres, or 100 litres for all five tyres.
Your car would fill all its tyres after doing about 4 km. We aren't going to solve the greenhouse problem with this one - unless you know different ...
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I wish I hadn't mentioned the nitrogen, I feel a bit of a cissy now. But I did not pay any extra or even ask for this. I noticed a sticker on the wall of the waiting room saying how marvellous nitrogen was for your car and sex life etc.
Thank you for posting your comment about Continental tyres Bill Payer. I haven't heard anything yet, but I expect they will say no one else has had any trouble. I will now be able to tell them something different!
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I wish I hadn't mentioned the nitrogen I feel a bit of a cissy now.
Dont worry about it, Costco filled my tyres with N, even used the fancy green valve caps, (which dont match the colour of my car). As I check my pressures weekly with a preset pump I have contaminated my N with real air but dont notice any difference whatsoever. Nitrogen probably makes a difference if you are driving a jet aircraft or F1 car but for the rest of us I put it down to "marketing".
Edited by Old Navy on 04/05/2009 at 19:25
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just checked 2 web sites the tyre pressures on my vehicle should be
33 front ; 30 back on one and 34/31 on the other - so which is right and if I'm carrying a heavier load than normal, without referring to my manual, should it be higher and roughly by how much ?
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If you cant find, or dont have access to the manual, there should be a sticker on the car somewhere giving all the presures for various loads. I assume you will have the car with you when you top up your tyres.
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Wotspur, is your car a Passat? My Passat tyres should be 33.5 front and 30.5 rear. This is after translating it from bars which is on the fuel flap. In your case they are either rounding up or down.
I don't bother increasing the pressures if I have a heavier load, you can't keep messing about for shortish runs. If I was going to Cannes (I wish) with a heavy load, I would bother.
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Allowing for the fact that our atmosphere is made up of Nitrogen, 78.082% by volume of dry air, 75.3% by weight in dry air, would the use of 100% Nitrogen, affect the pressures the tyres should be set at?
Something is telling me that 75.3% would put an element (sic) of pressure difference...
... and yes.... I do know about temperature causing pressure difference, in fact theres another question - with Nitrogen, does the ambient temperature make a greater or lesser difference over good old air?
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It's far more determined by the moisture content than the gas, but I'll let someone who actually understands this a little better than I do explain.
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Does the ambient temperature make a greater or lesser difference over good old air?
I don't think you could detect any differences in your motoring with nitrogen in your tyres rather than air. The main advantage is that N2 will (should) be from a cylinder and bone-dry; also, containing no moisture or oxygen, no corrosion will occur inside the tyre.
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>>ontaining no moisture or oxygen, no corrosion will occur inside the tyre.
Less moisture, less oxygen, less corrosion. There's 1 atmosphere of ambient in there to begin with!
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True. I don't suppose many garages purge the tyres before fitting ...
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I have yet to go through the joy of undoing my nuts following a trip to kwik fit. I asked if he had torqued the nuts up, and he picked up the torque wrench and proved they went click...
In too much of a hurry to complain at the time - I have a 2' breaker bar in the car at all times...
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I like my tyre pressures to be set at the high-speed / max load setting (36 front / 41psi rear).
Just had the first service, thought things felt a little mushy on the drive home. Checked the pressures and they were at 32 all round ... which is 3psi BELOW the recommended pressure.
I don't trust anyone with my tyre pressures :-|
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