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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Tyre sidewall marking
Been trying to understand tyre markings on my trailer tyres.
It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? |
#2
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Tyre sidewall marking
The 75 figure is the aspect ratio and dimensionless.
-- DB. |
#3
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Tyre sidewall marking
"Osprey" wrote in message ups.com... Been trying to understand tyre markings on my trailer tyres. It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? The 75 refers to the profile and is a measurement of the height of the sidewall/tyre width given as a percentage. Adam |
#4
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Tyre sidewall marking
On Oct 30, 5:53 pm, Osprey wrote:
Been trying to understand tyre markings on my trailer tyres. It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? http://www.google.co.uk/search?q=tyre+sidewall+markings Mathew |
#5
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Tyre sidewall marking
In message . com,
Osprey writes Been trying to understand tyre markings on my trailer tyres. It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? Surprisingly difficult to find good sites with info on tyre wall markings - KwikFit have a tiny subsection and doesn't address the OPs query. Dunlop.co.uk also had minimal info. But, http://www.tyres-online.co.uk/tech.asp (no connection etc.) provides all the info. you need I think. -- Si |
#6
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Tyre sidewall marking
In an earlier contribution to this discussion,
Osprey wrote: Been trying to understand tyre markings on my trailer tyres. It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? As others have said, the 75 refers to the aspect ratio as a percentage. So the 'height' of the tyre is 75% of 205 = 153.75 So the overall diameter is (14 x 25.4) + (153.75 x 2) = 663 mm Not quite the 635 which you measured, but a lot closer than 505! For tyre markings in general, see http://www.ntta.co.uk/law/trailers/tyres.htm -- Cheers, Roger ______ Email address maintained for newsgroup use only, and not regularly monitored.. Messages sent to it may not be read for several weeks. PLEASE REPLY TO NEWSGROUP! |
#7
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Tyre sidewall marking
Osprey wrote:
Been trying to understand tyre markings on my trailer tyres. It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? If I might just throw in my own recommendation, take a look at the following:- http://www.carbibles.com/tyre_bible.html It is by far the most comprehensive explanation I have found of all tyre sidewall markings, sizes, wheel configuration, offset, etc. -- Dave N N.B. Mail sent to "nospam" will be rejected. The Reply-To address works. |
#8
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Tyre sidewall marking
On Oct 30, 9:47 pm, Dave N wrote:
If I might just throw in my own recommendation, take a look at the following:- http://www.carbibles.com/tyre_bible.html It is by far the most comprehensive explanation I have found of all tyre sidewall markings, sizes, wheel configuration, offset, The whole Car Bible series is well worth a bookmark... (coupled with http://www.batteryfaq.org/ for car battery info!) Mathew |
#9
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Tyre sidewall marking
Huge (Huge ) gurgled happily, sounding much
like they were saying: Been trying to understand tyre markings on my trailer tyres. It is marked as 205 75 R14 That should mean (I think) rim diam is 14", height of tyre is 75mm and width is 205mm. Form this you would assume overall diam of Tyre would be 14" (i.e. 355mm) plus 2 x 75mm so overall width of 505mm Yest if I measure it the overall width is 635mm significantly different. Anybody know why the discrepancy? The "75" is the aspect ratio. The lower the number, the lower the sidewalls. And is given as a percentage of the nominal tread width. So, in the OP's example, you've got 355mm + 2x(75% of 205mm) = 355+2x154 = 663mm. Tyre sizes must drive the metrication fascists bonkers; three numbers, one metric, one imperial and one dimensionless Not exactly "dimensionless". not to mention the speed rating which is an arbitrary index, not in alphabetical order, to a speed in mph (that's the "R"). No, that's R-for-Radial. There's a piece of information we're not given in the original post - the load & speed ratings. A decade or more ago, tyres used to be typically labelled "205/75 HR14" - where the H was the speed rating. Now they're more typically "205 75 R14 87H" - where the 87 is the load rating and the H the speed rating. http://www.blackcircles.com/general/sidewall |
#10
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Tyre sidewall marking
Huge (Huge ) gurgled happily, sounding much
like they were saying: Tyre sizes must drive the metrication fascists bonkers; three numbers, one metric, one imperial and one dimensionless Not exactly "dimensionless". So, what are it's dimensions? Acre-feet? Lightyear-barns? Barrels per kiloparsec? It's a ratio, and therefore dimensionless. It's one of those "it is and it isn't" numbers, I reckons. No, on it's own, it is dimensionless, but taken as a whole at least it's easy to turn into an absolute dimension - unlike the load rating number... |
#11
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Tyre sidewall marking
On Nov 1, 10:32 am, Adrian wrote:
Huge (Huge ) gurgled happily, sounding much like they were saying: Tyre sizes must drive the metrication fascists bonkers; three numbers, one metric, one imperial and one dimensionless Not exactly "dimensionless". So, what are it's dimensions? Acre-feet? Lightyear-barns? Barrels per kiloparsec? It's a ratio, and therefore dimensionless. It's one of those "it is and it isn't" numbers, I reckons. No, on it's own, it is dimensionless, And remains so whoever's company it keeps. but taken as a whole A whole lot of nonsene, maybe. at least it's easy to turn into an absolute dimension You can use the ratio to calculate one dimensions from another. The ratio itself remains dimensionless, it does not get turned into anything. Maths wasn't your strong point at school, then. MBQ |
#12
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Tyre sidewall marking
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#13
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Tyre sidewall marking
On Nov 1, 12:36 pm, Adrian wrote:
" ) gurgled happily, sounding much like they were saying: Maths wasn't your strong point at school, then. I've never lied about having failed A-level Maths, 'tis true. Nor have I, LOL! OK, I didn't quite fail but got a D due to a bout of complacency and insufficient revision. I got an A the second time round! MBQ |
#14
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Tyre sidewall marking
On 31 Oct 2007 22:03:34 GMT, Huge wrote:
Tyre sizes must drive the metrication fascists bonkers; We forced them to drive the last of those Alfasud Tiis with their 350mm rims, until they realised that rims ought to be sized in inches, if you ever wanted to find tyres to fit. That taught 'em. |
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