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DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 682
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Just looking at changing vehicles from a D4 with 19" to one with 20".
My preferred tyre s the Duratrac but interestingly the fuel use and weather ratings go from a C and C for the 19" to E and E for the 20"
Anyone have any idea why? Would have thought they would be the same.
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29th Jun 2023 10:41 am |
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LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23825
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Whilst the rolling radius will be very similar, the footprint isn’t the same and that’s what makes the difference for wet grip and braking.
I suspect the sidewall depth is also a factor in the noise output of a tyre. 2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography (now semi-retired)
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29th Jun 2023 12:34 pm |
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DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 682
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LT,
Thanks for that, the tyres I was looking at are both 255's in width (255 55 19 and 255 55 20). I know the rolling radius will be slightly larger, but thought that the width being the same would mean the area in contact with the road would be damn close to the same.
Just surprised that there is so much of a difference
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29th Jun 2023 1:01 pm |
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LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23825
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Yeah, in the example of a comparison between 255-55-19 & 255-50-20 only the sidewall is different by half an inch.
So the footprint can't be much if any different:?
Are they both the same speed rating? 2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography (now semi-retired)
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29th Jun 2023 1:29 pm |
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DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 682
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Yes, same codes. An odd one, perhaps the site selling them (oponeo.ie) has not lifted the correct info from the manufacturers page - I must check that out
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29th Jun 2023 1:51 pm |
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LT
Member Since: 31 Dec 2005
Location: South West
Posts: 23825
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I know that a manufacturer will sometimes make a tyre with a specific specification for a manufacturer, such a better dry grip etc. Which is why you’ll see the manufacturers name against the tyre on the website.
Whilst visually the tyres will look identical the compound will be different, with for example more or less silica and other agents.
This will affect the performance and thus the labelling.
Same applies for speed rating. The compound is different. 2006 D3 HSE (Original & still the best)-GONE
2010 D4 HSE (A bit bling)-GONE
2014 D4 HSE (Almost too bling)-GONE
2015 D4 HSE (A heated what?)-GONE
2016 D4 Landmark (Written Off)-GONE
2016 D4 Landmark (Surely the last!) PD1881 rims-GONE
2017 FFRR SDV8 Autobiography (now semi-retired)
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29th Jun 2023 2:15 pm |
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johnlad
Member Since: 02 Dec 2016
Location: blackpool
Posts: 408
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Taller tyre takes more energy to start rolling and has more momentum to stop.
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30th Jun 2023 1:20 pm |
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ronp
Member Since: 29 Nov 2006
Location: North Yorkshire
Posts: 15263
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Had been thinking on changing out my AT3s to Duratecs, but the speed rating (& potential insurance implications) put me off.
In my size -
Duratecs are Q rated (max 99mph)
AT3s are V rated (max 149mph)
Not that I travel at anywhere near these speeds. ...... always on the road less travelled 🚧
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30th Jun 2023 2:02 pm |
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