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Tyres.

Ali T said:
I’d need 275/30/19 for the rears, not much of a sidewall there. :)
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I'd be tempted to take them up to 40 next time if you've got clearance. Another flat here this morning and guess what?

It's on our only 30s: so let's hope the council won't have to shell out for another rim.

I'll photograph the hole when the rain stops.
 
30 and 40 profile tyres are a nonsense, a real triumph of style over substance. They ruin the ride quality, make rims vulnerable to damage and do nothing for handling.
 
guest said:
Wet braking stopping distance from 30mph VW Golf.

Continental: 31.7 metres
Nankang: 33.8 metres
GT Radial: 35.8 metres
Wanli, Triangle and Linglongs: 40.2 metres

Nearly 30% longer to stop on budget!! This is on brand new tyres. Plenty data to suggest that those distances increase exponentially as tyres reaches legal min tread depth, with the budget brands dropping off more in performance.

From Autocar.

<<The Linglong equipped VW Golf Autocar used for its tests was still doing 27.8mph at the point where it had stopped on the Continentals. Overall the Continentals easily won, scoring top marks in all but one test. A consistent performance earned the GT Radials second place, but a wet lap time 3.4sec adrift of the Continentals indicated just how far even it falls short.
>
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This article sponsored by Continental Tyres Ltd? Sorry, my bullshit detector is pinging.
This bit:
The Linglong equipped VW Golf Autocar used for its tests was still doing 27.8mph at the point where it had stopped on the Continentals.
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Now if that is the case the car then went on to stop, from 27.8mph, in the remaining distance, 40.2-31.7 = 8.5 metres.
I haven't got out my laws-of-physics equations but if a Conti took 31.7m from 30-0 then a LingLong is not going to manage 27.8-0 in 8.5m, even though we all know that kinetic energy goes as the square of velocity. I suspect that 27.8mph to zero in 8.5m is better than 1g, and that ain't happening on a dry road, let alone a wet one. There's a flaw in these figures, they are either flawed measurements or inaccurately reported.
 
Might struggle with that, not much room as it is unfortunately. Cross climates not available in that size anyway.
stevec67 said:
30 and 40 profile tyres are a nonsense, a real triumph of style over substance. They ruin the ride quality, make rims vulnerable to damage and do nothing for handling.
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Don't disagree, however my car is an M sport and I don't think i could go up much and not get problems. Might get away with 35 but it would be close I think. I do have a set of 18" alloys with winter tyres on, might be better off selling the 19" rims which would more than pay for new 18" tyres.
 
My schoolboy physics, from v^2=u^2 +2as, gives decelerating from 27.8 mph to a stop in 8.5m is 9m/s/s. g is 9.81 m/s/s. Cars cannot exceed 1g using only cohesive forces (ie the real world), ask any first year engineering student. We therefore have to imagine that the LingLong went on to decelerate at about 0.9g when the Contis only managed about 0.3g, which is pretty impressive on a wet road but not 1g.

So sorry Autocar, these figures are wrong. Resubmit, this time showing working.
 
Fated.

All this talk of tyres and rubbish low profiles and now my wife just rang to say she has got to have 2 new tyres (45 section 19" Continental jobs) on her Qashqai. And all round brake pads too. As well as the MOT (passed that OK at least).

That's not a good start to the new credit card month!
 
And I thought it was only buyers of cheap tyres who ran them until they were illegal. Here we have a Qashqai on Contis that sounds as if it has failed the MoT on them. ;-P
 
guest said:
This thread focuses rather too much on high speed aquaplaning on limit handling and less so actual stopping.

ROSPA research suggest that there are 10x more accidents happen under 30mph than do at 70mph (80,000 vs 8,200).

For primarily around town pootlers, ultimate stopping distance may therefore be more important than ultimate ability to cope with aquaplaning.

Maybe here's the case for not using budget tyres...or indeed having the best tread on front, since this affects braking distance most, with Front brakes and tyres doing most of the stopping power. Sure the rear may stay true and straight - as you sail on into that dog/child etc

Wet braking stopping distance from 30mph VW Golf.

Continental: 31.7 metres
Nankang: 33.8 metres
GT Radial: 35.8 metres
Wanli, Triangle and Linglongs: 40.2 metres

Nearly 30% longer to stop on budget!! This is on brand new tyres. Plenty data to suggest that those distances increase exponentially as tyres reaches legal min tread depth, with the budget brands dropping off more in performance.

From Autocar.

<<The Linglong equipped VW Golf Autocar used for its tests was still doing 27.8mph at the point where it had stopped on the Continentals. Overall the Continentals easily won, scoring top marks in all but one test. A consistent performance earned the GT Radials second place, but a wet lap time 3.4sec adrift of the Continentals indicated just how far even it falls short.

Given the average rain fall in the UK, it's well worth thinking twice before fitting super-budget tyres on your vehicle. If you save ?75 fitting 4 budget tyres you only save 0.05 pence a mile over a 12,000 mile life of the tyre. With the risk of an expensive insurance excess and loaded premium for the next 5 years, not to mention what could happen in a worse case scenario, is it really worth it? >>
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Pretty much exactly my point in post #99
 
JensenHealey said:
Fated.

All this talk of tyres and rubbish low profiles and now my wife just rang to say she has got to have 2 new tyres (45 section 19" Continental jobs) on her Qashqai. And all round brake pads too. As well as the MOT (passed that OK at least).

That's not a good start to the new credit card month!
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Hope you’re having a word with her about her driving style...
 
It's all those Fast and Furious videos she keeps watching on repeat, and going out at 2am to find a big wet roundabout where she can practice her Scandinavian Flick.
 
stevec67 said:
My schoolboy physics, from v^2=u^2 +2as, gives decelerating from 27.8 mph to a stop in 8.5m is 9m/s/s. g is 9.81 m/s/s. Cars cannot exceed 1g using only cohesive forces (ie the real world), ask any first year engineering student. We therefore have to imagine that the LingLong went on to decelerate at about 0.9g when the Contis only managed about 0.3g, which is pretty impressive on a wet road but not 1g.

So sorry Autocar, these figures are wrong. Resubmit, this time showing working.
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Can't be bothered with the schoolboy science.

F1 cars regularly hit 3G under braking due to aero and increased friction with rubber to surface interlock. Plenty of road cars can also exceed 1g braking in the in the real world. In short your assumptions are incorrect sionce they completely fail to take into account friction adhesion coefficient (mU) between road surface and silica tyre compound. Non schoolboy engineers state that this 'Velcro effect' enable tyres to key themselves into road surface and exceed the 1mU math you claim is limit - and that most modern premium tyres will support 1.2g deceleration at peak on dry road. Many cars record over 1g in published road tests, Go look at Road & Track test base.

E.g. Audi TT 60-0mph in 155ft, deceleration time 2.62s, av deceleration 10,23m/s or 1.04g.

On premium tyres of course.

A little Google also reveals that mU is not a constant with the rate of deceleration increasing as cars slow.

Get yer calculator out or, maybe just Look at these figures from Auto Bild - top 50 tyres dry and wet braking distances. There is a significant delta in braking distances wet and dry and that is completely consistent with above claims by Autocar

https://www.tyrereviews.co.uk/Article/2020-Tyre-Market-Overview-Braking-Test.htm

Try What car? - theme is the same.


Ditto Auto Express, who also compare new and part worn front tyre braking performance, noting that even with premium tyres, they also lose significant braking effect when at 6mm vs 2mm tread depths, increasing braking distance from 55mph to 50metres from 39metres on goodyear-shod Focus

https://www.autoexpress.co.uk/car-n...parison-choosing-the-right-tyres-for-your-car
 
guest said:
Can't be bothered with the schoolboy science.

F1 cars regularly hit 3G under braking due to aero and increased friction with rubber to surface interlock. Plenty of road cars can also exceed 1g braking in the in the real world. In short your assumptions are incorrect sionce they completely fail to take into account friction adhesion coefficient (mU) between road surface and silica tyre compound. Non schoolboy engineers state that this 'Velcro effect' enable tyres to key themselves into road surface and exceed the 1mU math you claim is limit - and that most modern premium tyres will support 1.2g deceleration at peak on dry road. Many cars record over 1g in published road tests, Go look at Road & Track test base.

E.g. Audi TT 60-0mph in 155ft, deceleration time 2.62s, av deceleration 10,23m/s or 1.04g.

On premium tyres of course.

A little Google also reveals that mU is not a constant with the rate of deceleration increasing as cars slow.

Get yer calculator out or, maybe just Look at these figures from Auto Bild - top 50 tyres dry and wet braking distances. There is a significant delta in braking distances wet and dry and that is completely consistent with above claims by Autocar

https://www.tyrereviews.co.uk/Article/2020-Tyre-Market-Overview-Braking-Test.htm

Try What car? - theme is the same.


Ditto Auto Express, who also compare new and part worn front tyre braking performance, noting that even with premium tyres, they also lose significant braking effect when at 6mm vs 2mm tread depths, increasing braking distance from 55mph to 50metres from 39metres on goodyear-shod Focus

https://www.autoexpress.co.uk/car-n...parison-choosing-the-right-tyres-for-your-car
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So the LingLongs are pulling 0.9g on a wet road between 27mph and zero, when the Contis are doing 0.3g between 30 and 0? Yeah, right. I don't care what an F1 car will do with aero, there is FA chance of a Golf pulling 0.9g on a wet road, regardless. Even schoolboy science proves that.
The Contis are better, no doubt, but not 0.9g better. Get your own calculator out.
 
JensenHealey said:
Fated.

All this talk of tyres and rubbish low profiles and now my wife just rang to say she has got to have 2 new tyres (45 section 19" Continental jobs) on her Qashqai. And all round brake pads too. As well as the MOT (passed that OK at least).

That's not a good start to the new credit card month!
Click to expand...


stevec67 said:
And I thought it was only buyers of cheap tyres who ran them until they were illegal. Here we have a Qashqai on Contis that sounds as if it has failed the MoT on them. ;-P
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JH clearly states car has passed MoT, so it is probably an advisory.
 
stevec67 said:
So the LingLongs are pulling 0.9g on a wet road between 27mph and zero, when the Contis are doing 0.3g between 30 and 0? Yeah, right. I don't care what an F1 car will do with aero, there is FA chance of a Golf pulling 0.9g on a wet road, regardless. Even schoolboy science proves that.
The Contis are better, no doubt, but not 0.9g better. Get your own calculator out.
Click to expand...

Think distance not Gs. Or wood and trees.
 
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