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New Tyres

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New Tyres
Charles P Offline
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#21
19-05-2021, 07:29 PM (This post was last modified: 20-05-2021, 10:13 AM by Charles P.)
(19-05-2021, 07:06 PM)Tony Griffiths Wrote:
(19-05-2021, 07:25 AM)Paul N-M Wrote: Blockley 350/19 25.95" dia x 3.7"
Longstone 350/19 26.33" dia x 3.6"

From their info pages.

Whatever the literature says, in Hedd's picture the Longstone looks to be taller in wall height than the Blockley.
Optical illusion or perhaps very worn Blockleys?

c

NB - Edited to remove the wrongs maths  - mostly for the benefit of duff search results!
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Alan Offline
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#22
19-05-2021, 07:31 PM
Overall diameter isn’t what determines the rolling circumference of a tyre. It’s the position of the belting which does that. So, from the published data it’s impossible to say which of these tyres gives the lowest gearing. Having said that, I use blockleys and am very happy with them.
Alan Fairless
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tomcotez Offline
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#23
19-05-2021, 09:30 PM
I found that Blockley’s give a harder ride than longstones which are much more comfortable. I also prefer the look of the longstones.
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Tony Griffiths Offline
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#24
20-05-2021, 12:59 AM (This post was last modified: 20-05-2021, 01:01 AM by Tony Griffiths.)
(19-05-2021, 07:29 PM)Charles P Wrote:
(19-05-2021, 07:06 PM)Tony Griffiths Wrote:
(19-05-2021, 07:25 AM)Paul N-M Wrote: Blockley 350/19 25.95" dia x 3.7"
Longstone 350/19 26.33" dia x 3.6"

From their info pages.

Thanks for the information. In each case, the wall height is greater than the tread width meaning they are both (just) the opposite of low profile. But, as pointed out, the Blockley does have a "low-profile" look - and exceeds a 100% profile by a smaller margin than the Longstone.

Blockley wall height = 3.975". Tread width = 3.7". This gives a tyre wall height 0.125" less than the tread width = a profile of 90.4%
Longstone wall height - 3.665". Tread width = 3.6". This a wall tyre height 0.065" greater than the tread width = a profile of 101.8%

Whatever the literature says, in Hedd's picture the Longstone looks to be taller in wall height than the Blockley.
Optical illusion or perhaps very worn Blockleys?

You are correct - I transposed a couple of numbers and the correct calculation is shown. A picture is worth a thousand times an incorrect calculation!
http://lathes.co.uk
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Ray White Offline
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#25
20-05-2021, 09:22 AM (This post was last modified: 20-05-2021, 09:23 AM by Ray White.)
I have Avon 3.25 's on the front of my Swallow. They seem to make the steering nicer and more responsive.
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Hedd_Jones Offline
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#26
20-05-2021, 10:24 AM
I 'm a civil engineer. I have well trained eyes!
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Tony Griffiths Offline
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#27
20-05-2021, 01:37 PM
Can you run a tape around the two makes of tyre to check their circumference?
http://lathes.co.uk
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andrew34ruby Offline
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#28
20-05-2021, 09:33 PM
(20-05-2021, 01:37 PM)Tony Griffiths Wrote: Can you run a tape around the two makes of tyre to check their circumference?

Yes, but it doesn't give you a true comparison. It's to do with how a tyre deforms as is goes around.
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JonE Offline
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#29
20-05-2021, 09:44 PM
Surely as it deforms its circumference won't actually change, whilst its path might...?
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Tony Griffiths Offline
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#30
20-05-2021, 11:05 PM (This post was last modified: 20-05-2021, 11:07 PM by Tony Griffiths.)
(20-05-2021, 09:33 PM)andrew34ruby Wrote:
(20-05-2021, 01:37 PM)Tony Griffiths Wrote: Can you run a tape around the two makes of tyre to check their circumference?

Yes, but it doesn't give you a true comparison. It's to do with how a tyre deforms as is goes around.

Would a closer - if not perfect result - be obtained by measuring with the wheel on the ground and trapping the tape?
(20-05-2021, 09:33 PM)andrew34ruby Wrote:
(20-05-2021, 01:37 PM)Tony Griffiths Wrote: Can you run a tape around the two makes of tyre to check their circumference?

Yes, but it doesn't give you a true comparison. It's to do with how a tyre deforms as is goes around.

Would measuring with the wheel on the ground and the tape trapped beneath give a more accurate - if not perfect - result?
http://lathes.co.uk
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