A sneaky speeding crackdown.

izwozral said:
AAAAAAAAAAARRRRRRRRRGGGGGGGGGGGGHHHHHHHHHHH stop it stop it stop it, my head hurts with all this talk of rubber & spinning & roundness & gearing, write something interesting like the life of a ping pong ball or something. You will only get someone posting back with "awfully sorry dear chap but the blah blah blah blah can't be blah blah blah blah & if you don't agree then you are *^&$£""!!& (*$$%££^"! &&*^$ " and Admin will have to get all fatherly again, clip yer ears & send you off to bed again.
I could of course stop reading this thread but I am too nosey for that. If it helps, I have asked everyone in the whole world if they agree with you & guess what, they do, they really do, yes, you are not far off with your 5mph estimate. Okay? Good.
Click to expand...

You do realise that you're just making it funnier to keep this thread going now, doncha? :hammer::lol-049:
 
izwozral said:
AAAAAAAAAAARRRRRRRRRGGGGGGGGGGGGHHHHHHHHHHH stop it stop it stop it, my head hurts with all this talk of rubber & spinning & roundness & gearing, write something interesting like the life of a ping pong ball or something. You will only get someone posting back with "awfully sorry dear chap but the blah blah blah blah can't be blah blah blah blah & if you don't agree then you are *^&$£""!!& (*$$%££^"! &&*^$ " and Admin will have to get all fatherly again, clip yer ears & send you off to bed again.
I could of course stop reading this thread but I am too nosey for that. If it helps, I have asked everyone in the whole world if they agree with you & guess what, they do, they really do, yes, you are not far off with your 5mph estimate. Okay? Good.
Click to expand...

You didn't ask me! :sad::cry:
 
Gawd, any idjut with the slightest mathematical bent realises the the differential ratio will change logarithmically as the wheel diameter increases! Don't need a table to see that...:lol-053:
Getting a little tyred of this tread!
John
 
A quick glance suggests (which makes sense and is kind of obvious really) that (as the percentage difference of a fixed say 7mm tread difference between new and worn) on a large wheel/ tyre is a much lower percentage of the total diameter and circumference measurements... so that means that the difference in indicated speed due to wear IS there, but isn't that significant. So a huge lorry wheel isn't going to alter much (probably why there's no need for the Tachograph to need to be sophisticated to compensate as the error marging does not warrant it, helped further by a ceiling speed of 56mph limited).

Go to the other extreme of something like a 10" mini wheel and the effect is far greater. Also as another poster covered (and I have done myself as a yoof running 12" wheels on the front of a Mini instead of 10" - Rally and Rally-Cross stylee from back-in-the-day) if you change the diameter by using a wheel/tyre combo change then you can affect the accuracy of the speedo by rather a lot.

(A mini running 12" wheels is a much nicer drive on the open road btw - a heck of a lot less 'busy' due to the longer-legged gearing. You did have to put up with the tyres rubbing the arches on full lock as well. We didn't worry about the speedo hugely under-reading as a result, as back then iot was 'just' the Police to worry about, and they were far more interested in you just driving responsibly than being totally pedantic for Profit).
 
GRWXJR said:
A quick glance suggests (which makes sense and is kind of obvious really) that (as the percentage difference of a fixed say 7mm tread difference between new and worn) on a large wheel/ tyre is a much lower percentage of the total diameter and circumference measurements... so that means that the difference in indicated speed due to wear IS there, but isn't that significant. So a huge lorry wheel isn't going to alter much (probably why there's no need for the Tachograph to need to be sophisticated to compensate as the error marging does not warrant it, helped further by a ceiling speed of 56mph limited).

Go to the other extreme of something like a 10" mini wheel and the effect is far greater. Also as another poster covered (and I have done myself as a yoof running 12" wheels on the front of a Mini instead of 10" - Rally and Rally-Cross stylee from back-in-the-day) if you change the diameter by using a wheel/tyre combo change then you can affect the accuracy of the speedo by rather a lot.

(A mini running 12" wheels is a much nicer drive on the open road btw - a heck of a lot less 'busy' due to the longer-legged gearing. You did have to put up with the tyres rubbing the arches on full lock as well. We didn't worry about the speedo hugely under-reading as a result, as back then iot was 'just' the Police to worry about, and they were far more interested in you just driving responsibly than being totally pedantic for Profit).
Click to expand...

Lorry tyres have HUGE TREADS though, when all's said and done a lorry drive axle with a useable tread of 16mm will equate to a speed difference much the same as your bike tyre with a usable tread of 5mm. Presumably you change them at or before they are down to 2mm??
Lots of things to be considered as well as the pure mathematics.
 
Yes David, very interesting, in fact it is so interesting I am about to measure every tyre in Cheshire & compare them with your chart, even though I may get out of breath running after the bloody things.

Where's that bloody wall so I can smash my head against it.
 
No, not bored at all, I found your chart very enlightening & beautifully put together. Could you please draw up a chart for me that shows the longitudinal & thickitudinal growth of a nasal hair of a period of 2 weeks and any bearing that such growth has on climate change. I await with eager anticipation.
 
Effects of insanity caused by tyre equations.

Click on link above for more riveting discussions on this very interesting subject.
 
No-one is extracting the Michael, merely turning a very tedious thread finale into something little more light-hearted!:lol-053:
Mind you, I'm surprised that no-one has tried the Calculus using Maxima and Minima to calculate the tread wear rate on converging carriageways...
John
 
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Aww David just slapped me & I thought we were best friends too. :sad::sad:

P.S. And he's been spying on me. :scared::scared:
 
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