Inaccurate data (Autodata) used to service car

Mildly_Miffed

https://forums.moneysavingexpert.com/discussion/comment/82023389#Comment_82023389

Mental, isn't it? We've bought fuel by the litre for over forty years, yet we still insist on measuring how we use it by the gallon…

Worse, it's not even the same size gallon as the one country worldwide that uses gallons…

@James2k - so which other countries use psi rather than bar? Neither the pound, nor the inch, are used officially in any country but the US - so why on earth combine the two?

Iceweasel

I for one would be very happy to ditch all of the outdated Imperial units.

We started using SI units in the 70s - and we still haven't fully converted.

I'm a now-retired teacher and never used inches, pints, or pounds in my classroom, ever.

I started teaching in 1970.

Goudy

It's becoming more common to fill tyres with nitrogen these days.

There's no moisture in it to expand or condense, meaning it's more stable under all temperatures.

Your tyres don't just absorb heat from the sun, though they are black so will obviously absorb more energy from the sun (when it's out) than say white. They'll heat up with movement as the moisture inside get agitated and expands. They'll absorb heat from the road surface (which also tends to be black/dark and absorbs more energy from the sun). You'll get heat soak from the brakes as the discs radiate away excess heat.

Using nitrogen negates all that and as a bonus nitrogen molecules are far bigger. This means the tyre will hold pressure better. When tested they are around a third better at maintaining pressure.

And as a bonus, no moisture means less corrosion or the rims and valves.

Of course there's a cost to it, but your tyres pressures stay more stable under all conditions for much longer. I think I paid around a fiver per tyre not long back. If you say offset the monthly trip to the forecourt feed-o-meter airline, it's not that much more.

I check my pressures once a month and they tend to be bang on all year, since I've started using nitrogen I've not had to top them up.

iwaddo77

So I'm only ever setting the pump on the forecourt to 35 psi no matter the air temperature.

It will always be psi and mpg for me. [I have a separate question about calculating mpg in a PHEV as I never believe the in car numbers as I find they overstate the figures to make the car look better, maybe I'll start a new thread]

I need to consider an accurate gauge I can use to ensure consistency across forecourt air machines.

How do I fill them with nitrogen?

Goudy

Take it to a tyre shop. The national chains all offer it.

If you are looking for a good tyre pressure gauge, then look at the Jaco ElitePro Digital. It's certificated by the ANSI to be + or - 0.5% accurate. It's about £30.

PTP123

I wish all I had to worry about in life was a slight difference in tyre pressures

iwaddo77

https://forums.moneysavingexpert.com/discussion/comment/82024100#Comment_82024100

🤣 time to read and reply though 😉

oldagetraveller1

"Or fill them with nitrogen for less variation"

Which will be negligible when the atmosphere contains 78%/79% of nitrogen by volume anyway.

forgotmyname

Not just the temperature when it comes to tyres but the brand and even the model/batch number.

I find some tyres have a stronger/stiffer sidewall so you can drop the pressure a little and still get
even tyre wear which some other tyre brands are soft and need an increase in the pressure used.

Mildly_Miffed

https://forums.moneysavingexpert.com/discussion/comment/82024347#Comment_82024347

Quite.

IIRC when there was an F1 controversy a few years ago, it emerged they were using CO2.

Using N2 is pretty much an upsell scam.

@iwaddo - do you insist on pounds and ounces instead of kilos, fluid ounces and pints instead of litres, and pre-decimal money, too?