Inaccurate data (Autodata) used to service car

iwaddo77

I mix and match.

We drive in miles at a mph, I measure consumption in mpg

I convert bottled beer prices to pints for comparison

The kitchen scales are in grams, but I weigh myself in stones and pounds.

We tend to measure fluids in the kitchen in millilitres, litres and pints, depends on the recipe.

I measure in millimetres and metres

I inflate my tyres in psi

🤔

QrizB

Using nitrogen negates all that and as a bonus nitrogen molecules are far bigger.

@Goudy you've claimed this twice now.

Nitrogen molecules are "far bigger" than what, specifically?

MattMattMattUK

N2 5.2% larger kinetic diameter than O2, everything else is really an irrelevantly small percentage for tyres pressures.

Mildly_Miffed

If nitrogen really does prevent pressure loss through leaking of smaller molecules, then the air in your tyres would be an even higher proportion than the ~80% in the air at large…

@iwaddo - thanks for proving my point so eloquently… This country really is a pathetically wilful mish-mash of hangover dibnah measures, and sensible rest-of-world ones. If we had all just given our heads a wobble, we could have sorted this once and for all decades ago. Not even the 'merkins use stones, and almost all of their liquid measures are a different size to the ones we used to use but named the same. It's almost designed to confuse.

LightFlare

https://forums.moneysavingexpert.com/discussion/comment/82024718#Comment_82024718

If we could go back in time the. I agree, we would have been “better off” swapping everything when we changed our monetary system.

Wonder why we didn’t - was it due to industry (we did actually make stuff back then) saying it would be too costly to change all the tooling etc ?

As is, we have a bit of a mish mash - but we manage

I’m a bit like the OP is my use of old and “new”

USA does amuse me - they do also mix and match though on a subject which some love and some hate - is it a 5.56mm or a .223 - one man may have a .22, .38 .45 and another a 9mm or 10mm

iwaddo77

The combination of historical preference, public resistance, and legal mandates has resulted in the UK not fully adopting the metric system. While many sectors have metricated, the persistence of imperial units in certain areas continues to shape the measurement landscape in the UK.

Goudy

https://forums.moneysavingexpert.com/discussion/comment/82024681#Comment_82024681

What do you think that would be?

What would you normally fill your tyres with, air maybe?

Air is made up of around 20.9% oxygen and 78% nitrogen. The rest is made up of a few other elements like argon, a little carbon, helium, hydrogen, neon and methane.

The kinetic diameter of oxygen is 0.300nm and nitrogen 0.364nm. This might not seem like a massive difference but you need to factor in the density of the tyre construction.

As the nitrogen is larger, it's slower to move through the tyre construction, if at all. Though that depending on the tyre construction as well as what is inside.

This was always seen as an added benefit though, The main reason it's used it the lack of moisture. Nitrogen is significantly drier than air. Air contains oxygen and some hydrogen, or in plain words, water and we know that expands with heat, thus altering the pressure.

Now you have to put the two together to get a real time result. It's more stable to leaking and more stable under temperature, so the pressure stays stable for longer.

You are only replacing just over 20% of oxygen, argon, a little carbon, helium, hydrogen, neon and methane, but that's all of it. Well nearly, in high end motor sport they will actually use special "tyre driers" to purge the tyre completely before filling with nitrogen. Your local tyre specialist won't manage to purge it as well.