revtothelimit - motorbike forum

I'd guess its cause engines were typically done in cubic inches / freedom units. Cubic centimeters feels like less of a surrender to the commie metric system, despite it being both A) metric, and B)the same size as a millilitre.

Mr. Dazzle wrote: Fri Feb 07, 2025 8:11 am I'd guess its cause engines were typically done in cubic inches / freedom units. Cubic centimeters feels like less of a surrender to the commie metric system, despite it being both A) metric, and B)the same size as a millilitre.

Some of our Mint Imperial units still work bestest though. eg mph and psi. Them forrin equivalents, inc the Merkins with their squitty little 'gallons', are rubbish.

Edit: bhp is too.

Saga Lout wrote: Fri Feb 07, 2025 4:55 am Why do we use cc and litre for engine sizes? We should be consistent and use millilitres and litres.

(Or centilitres, )

Perhaps a change to cups or tablespoons?

Count Steer wrote: Fri Feb 07, 2025 8:44 am

Mr. Dazzle wrote: Fri Feb 07, 2025 8:11 am I'd guess its cause engines were typically done in cubic inches / freedom units. Cubic centimeters feels like less of a surrender to the commie metric system, despite it being both A) metric, and B)the same size as a millilitre.

Some of our Mint Imperial units still work bestest though. eg mph and psi. Them forrin equivalents, inc the Merkins with their squitty little 'gallons', are rubbish.

Edit: bhp is too.

My current car does tyre pressures in kPa on it's dashboard systems, the last one did too (funny that, what with it being basically the same model ). I could no doubt go into the settings and change it, but honestly I CBA and I've just recalibrated my thinking Correct pressure is 280kPa.

2.8bar if you prefer, which is what lots of pumps read in.

Count Steer wrote: Fri Feb 07, 2025 8:44 am

Mr. Dazzle wrote: Fri Feb 07, 2025 8:11 am I'd guess its cause engines were typically done in cubic inches / freedom units. Cubic centimeters feels like less of a surrender to the commie metric system, despite it being both A) metric, and B)the same size as a millilitre.

Some of our Mint Imperial units still work bestest though. eg mph and psi. Them forrin equivalents, inc the Merkins with their squitty little 'gallons', are rubbish.

Edit: bhp is too.

NY previous previous proper job (before a sideways shift, then redundancy) involved working in both imperial and metric.

Conversions never caused problems, oh no, never

We were designing printed circuit boards, where a track width of a single digit (e.g. "8 thou") is much easier to determine (by the electronics engineer) and describe than its metric equivalent.

Mr. Dazzle wrote: Fri Feb 07, 2025 9:15 am

Count Steer wrote: Fri Feb 07, 2025 8:44 am

Mr. Dazzle wrote: Fri Feb 07, 2025 8:11 am I'd guess its cause engines were typically done in cubic inches / freedom units. Cubic centimeters feels like less of a surrender to the commie metric system, despite it being both A) metric, and B)the same size as a millilitre.

Some of our Mint Imperial units still work bestest though. eg mph and psi. Them forrin equivalents, inc the Merkins with their squitty little 'gallons', are rubbish.

Edit: bhp is too.

My current car does tyre pressures in kPa on it's dashboard systems, the last one did too (funny that, what with it being basically the same model ). I could no doubt go into the settings and change it, but honestly I CBA and I've just recalibrated my thinking Correct pressure is 280kPa.

2.8bar if you prefer, which is what lots of pumps read in.

40psi??

fecking hell, what are you driving, a Routemaster???

I was one of those 'lucky' ones that had to learn the traditional UK system and CGS and MKS.

At Uni we had an old, quite eccentric, physics lecturer who said 'Units? Bah. Nothing to be afraid of. Now, calculate the emf - in V/m and gauss - developed by a metal ship's mast. The mast is x cubits long, the ship is travelling through the earth's field on an ESE bearing at y leagues per fortnight. Crack on'.

Rockburner wrote: Fri Feb 07, 2025 9:24 am
40psi??

fecking hell, what are you driving, a Routemaster???

Yeah I was a bit surprised too, but that's the number. It's a fairly typical big German saloon.

The old one, which was nearly the same car (even the same wheel design) was 270kPa. For some reason petrol engines add those last 10kPa.

My point was why do we use a solid (or volume) measure, i.e. cubic centimetres, for small engines but use a liquid measure, i.e. litres, for larger engines? My guess is: because we do, that's why.

A cold beer's got twelve ounces, A good truck's got maybe three hundred thousand.

Rockburner wrote: Fri Feb 07, 2025 9:24 am

Mr. Dazzle wrote: Fri Feb 07, 2025 9:15 am

Count Steer wrote: Fri Feb 07, 2025 8:44 am

Some of our Mint Imperial units still work bestest though. eg mph and psi. Them forrin equivalents, inc the Merkins with their squitty little 'gallons', are rubbish.

Edit: bhp is too.

My current car does tyre pressures in kPa on it's dashboard systems, the last one did too (funny that, what with it being basically the same model ). I could no doubt go into the settings and change it, but honestly I CBA and I've just recalibrated my thinking Correct pressure is 280kPa.

2.8bar if you prefer, which is what lots of pumps read in.

40psi??

fecking hell, what are you driving, a Routemaster???

My car is the first car I've ever had where the front and back tyres are different pressures, 43 psi front, 33 psi rear. Bloody Germans

Saga Lout wrote: Fri Feb 07, 2025 9:53 am My point was why do we use a solid (or volume) measure, i.e. cubic centimetres, for small engines but use a liquid measure, i.e. litres, for larger engines? My guess is: because we do, that's why.

Litres aren't a liquid measure, they're also a measure of volume. Hence why you have balloons measured in litres for example.

My T6 Kombi runs 58psi in the front and somewhere between 50 and 58psi in the back.

Pirahna wrote: Fri Feb 07, 2025 10:32 am My T6 Kombi runs 58psi in the front and somewhere between 50 and 58psi in the back.

High or low profile tyres?

I "believe" (but not sure) that lower profile tyres would need a higher pressure to ensure that any bigger bumps don't incur tyre-carcass > wheel rim interfaces.

I was gonna say mine aren't low profile, but that's not true, they probably are - it's just that our mental calibration of what 'low profile' means has shifted. They're 255/35.

They're also lined with noise abating foam

All of which makes them nearly £300 to replace when you get a puncture

Rockburner wrote: Fri Feb 07, 2025 12:00 pm

Pirahna wrote: Fri Feb 07, 2025 10:32 am My T6 Kombi runs 58psi in the front and somewhere between 50 and 58psi in the back.

High or low profile tyres?

I "believe" (but not sure) that lower profile tyres would need a higher pressure to ensure that any bigger bumps don't incur tyre-carcass > wheel rim interfaces.

215/60/17 standard VW fitment. I had some 70 profile tyres on the Crafter which were at 70psi.

Mr. Dazzle wrote: Fri Feb 07, 2025 12:42 pm I was gonna say mine aren't low profile, but that's not true, they probably are - it's just that our mental calibration of what 'low profile' means has shifted. They're 255/35.

They're also lined with noise abating foam

All of which makes them nearly £300 to replace when you get a puncture

And they will need replacing. Same size as mine, and they last about 10k miles.

Cousin Jack wrote: Fri Feb 07, 2025 1:27 pm

Mr. Dazzle wrote: Fri Feb 07, 2025 12:42 pm I was gonna say mine aren't low profile, but that's not true, they probably are - it's just that our mental calibration of what 'low profile' means has shifted. They're 255/35.

They're also lined with noise abating foam

All of which makes them nearly £300 to replace when you get a puncture

And they will need replacing. Same size as mine, and they last about 10k miles.

Did 18k on the last set before giving the car back, they still had 3.1mm left. Fleet services have got a nifty little doodad in the floor, you drive over it as you go into the returns bay and it measures all four tyres.

I was worried for a moment, 'cause you have to give the cars back with >3mm of tread, but I wasn't aware the 18 month leases had a bigger tread wear allowance and I could have gone down to 2mm. Shoulda done some doughnuts in the carpark.

This was on a 250bhp rear wheel drive car too and I wouldn't say I drive like a granny.

Pirahna wrote: Fri Feb 07, 2025 1:19 pm

Rockburner wrote: Fri Feb 07, 2025 12:00 pm

Pirahna wrote: Fri Feb 07, 2025 10:32 am My T6 Kombi runs 58psi in the front and somewhere between 50 and 58psi in the back.

High or low profile tyres?

I "believe" (but not sure) that lower profile tyres would need a higher pressure to ensure that any bigger bumps don't incur tyre-carcass > wheel rim interfaces.

215/60/17 standard VW fitment. I had some 70 profile tyres on the Crafter which were at 70psi.

My Mazda has 225/45R19, the slightly lower spec model has 225/55R17, the manual says they both need 33psi.

Saga Lout wrote: Fri Feb 07, 2025 1:34 pm

Pirahna wrote: Fri Feb 07, 2025 1:19 pm

Rockburner wrote: Fri Feb 07, 2025 12:00 pm

High or low profile tyres?

I "believe" (but not sure) that lower profile tyres would need a higher pressure to ensure that any bigger bumps don't incur tyre-carcass > wheel rim interfaces.

215/60/17 standard VW fitment. I had some 70 profile tyres on the Crafter which were at 70psi.

My Mazda has 225/45R19, the slightly lower spec model has 225/55R17, the manual says they both need 33psi.

Your car isn't a van. I only made the original comment on reply to someone who was surprised at higher tye pressures. From memory I think my Caddy ran the fronts at 40psi. My Duster has the same size tyres as the T6 and runs 33psi.