9 July 2025
Fake News or False Precision?
20 April 2022
How to weigh a car using a tape measure and a tyre pressure gauge
There are two pretty good ways to weigh a car:
- Drive it to the nearest public weighbridge and wait your turn.
- Look up the manual under General Specifications, ‘kerb weight’
But let's suppose the nearest public weighbridge is fifty miles away and you've lost the manual (and temporarily forgotten how to use public libraries and the Internet) and the burning urge to weigh your car just won't go away- what can you do about it?
The good news is, you need hardly any equipment. All you need, for a reasonably accurate result is:
- a hand-held tyre pressure gauge which can be analogue or digital
- a retractable steel measuring tape
- a calculator, pencil and paper, or a good head for mental arithmetic
The method
- Park the car on some clean, level concrete
- Observe that the car is held up by its four tyres (!)
- Measure the width of the tread of one tyre: e.g. 6 inches
- Measure the length of tread in contact with the ground: e.g. 7 inches
- Work out the area of tread touching the ground: e.g. 6 x 7 = 42 sq ins
- Now use the gauge to measure the tyre pressure: e.g. 25 psi (pounds per square inch)
- This tyre is therefore supporting 42 x 25 = 1,050 pounds
- Repeat for the remaining three tyres and add the four results together for the total weight.
- Front tyres carry more weight than rear: e.g. 1,050 + 1,050 + 900 + 900 = 3,900 pounds
If you are in a hurry, just measure one front tyre and the rear tyre on the same side. Sum them together and multiply by two. This works because cars tend to be left/right symmetrical.
The method can be used on a wide range of vehicles, such as:
- Cars, pickups, minibuses, buses, vans, lorries, old Bullnose Mercedes trucks, articulated trucks including effing-great eighteen-wheelers that shouldn’t be allowed on the roads, garbage collectors, tankers (full or empty), concrete pumps and aeroplanes, but not railway engines, steam-rollers or seaplanes with their floats down.
To weigh your seaplane...
You will need slightly different equipment. Forget the pressure gauge. The thing has floats, not tyres. The steel tape measure will still come in handy though:
- Procure an extremely large displacement tank and fill it with water.
- Using a crane, gently lower your stupid seaplane into the tank.
- Collect the displaced water in another smaller tank.
- Measure the volume of displaced water. (This is where your steel tape measure comes in).
- Apply Archimedes Principle to obtain the weight of the blasted seaplane, shouting Eureka at the appropriate moment, if you like.
Motorbikes are tricky too...
because they fall over. To weigh your motorbike, if you really must:
- Get a set of bathroom scales.
- Park your bike with the kickstand resting on the scales.
- Measure the area of both tyre ‘footprints’, as above.
- Measure the tyre pressures.
- Calculate the weights on front and rear tyres as above.
- Add these to the reading on the bathroom scales.
- Job done.
While you’re hanging around like a lemon with the bathroom scales, you can weigh any convenient bicycle by the simple method of:
- standing on the scales and noting your weight.
- picking up the bicycle and noting the combined weight.
- subtracting your weight from the combined weight.
This method can also be used to weigh dogs, cats, sacks of wheat, sea turtles and children, but not hamsters or postage stamps, because the difference is too small to register on bathroom scales.
To weigh your hamster, use the kitchen scales instead. Can I go now?
21 October 2021
The Three Jars - Being an Anthology
Just one of twenty-odd familiar nursery rhymes uniquely shredded and illustrated by Douglas McClure. Available on Amazon "The Three Jars - Being an Anthology" by Douglas McClure. Check it out!
29 March 2019
The New Welsh Sphinx
Among this morning's Google selection of tailored appropriate advertisements, I find this one suggesting a trip to Wales. This might be a nice idea, but all I'm seeing is a gy-normous cat with a human head and hands. A latter-day Sphinx, maybe?
9 May 2017
Heard in Heaven
Jesus: I think you had it with you when we went to Chipping Camden.
God: Ah yes, there it is! Thanks Son.
17 September 2016
The Punchary, Al Mansoura
9 August 2014
Mary, Mary, quite contrary...
27 July 2013
Knees, Plungers & Aliens
The old way
A long time ago, I studied photography. I used a manual SLR camera, took light measurements (incident and reflected), applied filters, adjusted focus, aperture and exposure, developed my own negatives, mixed my own chemicals, did my own darkroom work and, occasionally, achieved some pretty creditable results, none of which appear on this page.
Exterminate... Exterminate...
Sights unseen
And finally
Bull-neck and the Blue Lagoon
More random photographs
Dragonhide Farm mattered once.No-one remembers why.
28 January 2012
Still Life with Wheelbarrow, Truck and Candelabra
I have no idea what the candelabra was doing there, perched on a half demolished wall in Muntazah, and judging from its very French shrugging posture, it probably didn't know either. Even within the category of 'things you'd miss if you were driving a car', this little tableau was unexpected, to say the least.
If you have lost a candelabra and suspect this might be it, let me know and I'll take the same walk next weekend. If it's still there, I'll retrieve it for you.
Same goes for the wheelbarrow.
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