BlackCircles tyres... fitted service

Biggus_Dickus

AdrianC said:

Higher tyre pressures usually mean lower rolling resistance - but at the expense of ride quality and grip.

Why didn't he just look at the sticker that would have been on the car...?

I really don’t understand ‘ECO tyre pressure settings’;...the info in the manual says ECO (higher) pressure for best fuel economy whilst for best possible noise and travelling comfort conditions use lower pressures.

The only tyre pressures that I’m interested in are the ‘safest’ tyre pressures!...but what are they?

If using higher ECO tyre pressures just to save a few quid a year in any way compromise the vehicles safety then I’m not interested, but that specific  info seems very hard to come by.

Perhaps the ECO tyre pressure info should come with the following caveat:

ECO pressures: may save you an indeterminate amount of cash. However, due to decreased grip and increased braking distance you and/or your passengers may die horribly ! 

Takmon

Biggus_Dickus said:

AdrianC said:

Higher tyre pressures usually mean lower rolling resistance - but at the expense of ride quality and grip.

Why didn't he just look at the sticker that would have been on the car...?

I really don’t understand ‘ECO tyre pressure settings’;...the info in the manual says ECO (higher) pressure for best fuel economy whilst for best possible noise and travelling comfort conditions use lower pressures.

The only tyre pressures that I’m interested in are the ‘safest’ tyre pressures!...but what are they?

If using higher ECO tyre pressures just to save a few quid a year in any way compromise the vehicles safety then I’m not interested, but that specific  info seems very hard to come by.

Perhaps the ECO tyre pressure info should come with the following caveat:

ECO pressures: may save you an indeterminate amount of cash. However, due to decreased grip and increased braking distance you and/or your passengers may die horribly ! 

There are many different factors that effect what the safest possible tyre pressure is and that varies depending on the temperature outside, the number of passengers and load in the car, the composition of the tyre etc. So the range of pressures that are stated by the manufacturer are all considered to offer a safe amount of grip and braking performance. If you wanted to have the safest pressure at all times you would be constantly adjusting the pressures as the number of passengers changed in the car and depending on the outside temperature of the day which i'm sure you don't do. Also it would be almost impossible to determine what the safest possible pressure is at all times as there are so many factors involved.
So your best bet is just to set it in mid range and don't adjust it unless you have a large change in the loading of the car.

Also it's worth noting these pressures are all advised based on the original tyres supplied by the manufacturer and can vary if you fit a different brand/model to the car. 

AdrianC

Biggus_Dickus said:

AdrianC said:

Higher tyre pressures usually mean lower rolling resistance - but at the expense of ride quality and grip.

Why didn't he just look at the sticker that would have been on the car...?

I really don’t understand ‘ECO tyre pressure settings’;...the info in the manual says ECO (higher) pressure for best fuel economy whilst for best possible noise and travelling comfort conditions use lower pressures.

The only tyre pressures that I’m interested in are the ‘safest’ tyre pressures!...but what are they?

They're all "safe".

If you're using the car to the very edges of adhesion, then you may find trial and error helps you set the appropriate pressures for your track day...

Perhaps the ECO tyre pressure info should come with the following caveat:

ECO pressures: may save you an indeterminate amount of cash. However, due to decreased grip and increased braking distance you and/or your passengers may die horribly !

Mmm...

onlyfoolsandparking

I run 36psi all round on my cars and it seems to work well, different thing altogether regarding bike tyres. On 'track' days I run my bike tyres around 20psi IF it's a warm dry day, fast road riding is 30 in front and  32-34 rear and normal riding 36 front 42 rear. Ultimately there are infinite combinations with many factors to take into account, rider weight, suspension set up, weather temperature, wet or dry surface, I don't think those parameters apply to the majority of road cars unless you've borrowed an F1 car for the weekend.   

Biggus_Dickus

AdrianC said:

Biggus_Dickus said:

AdrianC said:

Higher tyre pressures usually mean lower rolling resistance - but at the expense of ride quality and grip.

Why didn't he just look at the sticker that would have been on the car...?

I really don’t understand ‘ECO tyre pressure settings’;...the info in the manual says ECO (higher) pressure for best fuel economy whilst for best possible noise and travelling comfort conditions use lower pressures.

The only tyre pressures that I’m interested in are the ‘safest’ tyre pressures!...but what are they?

They're all "safe".

If you're using the car to the very edges of adhesion, then you may find trial and error helps you set the appropriate pressures for your track day...

Perhaps the ECO tyre pressure info should come with the following caveat:

ECO pressures: may save you an indeterminate amount of cash. However, due to decreased grip and increased braking distance you and/or your passengers may die horribly !

Mmm...

How safe is safe?...it’s not a word that appears anywhere in the owner manual ‘tyre pressure section’.

The crux of my question, and I still don’t  know the answer, is: would increasing the tyre pressures by 5psi on my daughters Volvo have any significant effect on stopping distances, given the same set of conditions?

It’s never going to be an exact science and I’m fully aware that pressures increase as the tyres get hotter but nonetheless I still think it’s a valid question.

My ECO caveat comment was tongue in cheek btw, but nonetheless with a serious undertone.

I might try a few experiments on my next track day.

I forgot to answer your question about the tyre fitter: as I stated upthread he had a Smart App apparently. I assumed, perhaps wrongly, the his App was Smart enough to  give him all the info that’s available on the cars  pressure info ‘sticker’.

He said that he was strictly forbidden to touch the doors or enter the vehicle in any way;...CV19 rules I assumed.

I don’t know how he arrived at a figure of 36psi but that’s what he put in. He was extremely large, dour and morose and looked thoroughly miserable as it had been lashing down all day,...so I didn’t query it. I’ve dodged a few spanners in my time and didn’t fancy dodging another one.

To be fair, he did carry out the job with some efficiency.

 

 

 

 

 

 

Takmon

Biggus_Dickus said:

AdrianC said:

Biggus_Dickus said:

AdrianC said:

Higher tyre pressures usually mean lower rolling resistance - but at the expense of ride quality and grip.

Why didn't he just look at the sticker that would have been on the car...?

I really don’t understand ‘ECO tyre pressure settings’;...the info in the manual says ECO (higher) pressure for best fuel economy whilst for best possible noise and travelling comfort conditions use lower pressures.

The only tyre pressures that I’m interested in are the ‘safest’ tyre pressures!...but what are they?

They're all "safe".

If you're using the car to the very edges of adhesion, then you may find trial and error helps you set the appropriate pressures for your track day...

Perhaps the ECO tyre pressure info should come with the following caveat:

ECO pressures: may save you an indeterminate amount of cash. However, due to decreased grip and increased braking distance you and/or your passengers may die horribly !

Mmm...

How safe is safe?...it’s not a word that appears anywhere in the owner manual ‘tyre pressure section’.

The crux of my question, and I still don’t  know the answer, is: would increasing the tyre pressures by 5psi on my daughters Volvo have any significant effect on stopping distances, given the same set of conditions?

It’s never going to be an exact science and I’m fully aware that pressures increase as the tyres get hotter but nonetheless I still think it’s a valid question.

My ECO caveat comment was tongue in cheek btw, but nonetheless with a serious undertone.

I might try a few experiments on my next track day.

I forgot to answer your question about the tyre fitter: as I stated upthread he had a Smart App apparently. I assumed, perhaps wrongly, the his App was Smart enough to  give him all the info that’s available on the cars  pressure info ‘sticker’.

He said that he was strictly forbidden to touch the doors or enter the vehicle in any way;...CV19 rules I assumed.

I don’t know how he arrived at a figure of 36psi but that’s what he put in. He was extremely large, dour and morose and looked thoroughly miserable as it had been lashing down all day,...so I didn’t query it. I’ve dodged a few spanners in my time and didn’t fancy dodging another one.

To be fair, he did carry out the job with some efficiency.

 

 

 

 

 

 

Well they aren't going to mention "safe" tyre pressures because then that would imply any tyre pressures not mentioned as safe are unsafe. All the pressure they specify are safe and they are would not be allowed to recommend pressures that were not safe. 

But you may find this interesting:

http://article.sapub.org/10.5923.j.ijtte.20130202.01.html

The conclusion was that the recommended pressure and 20% below offered similar stopping distances but 20% above noticeably increased the stopping distance. 
But don't forget underinflated tyres will provide worse lateral grip so a pressure near the middle of the recommended range would provide a good combination of both. 
You could fine tune this on a track day if you had suitable measuring equipment but not sure how effective this would be considering a change in conditions after you leave the track would change the results.

Biggus_Dickus

Takmon said:

Biggus_Dickus said:

AdrianC said:

Biggus_Dickus said:

AdrianC said:

Higher tyre pressures usually mean lower rolling resistance - but at the expense of ride quality and grip.

Why didn't he just look at the sticker that would have been on the car...?

I really don’t understand ‘ECO tyre pressure settings’;...the info in the manual says ECO (higher) pressure for best fuel economy whilst for best possible noise and travelling comfort conditions use lower pressures.

The only tyre pressures that I’m interested in are the ‘safest’ tyre pressures!...but what are they?

They're all "safe".

If you're using the car to the very edges of adhesion, then you may find trial and error helps you set the appropriate pressures for your track day...

Perhaps the ECO tyre pressure info should come with the following caveat:

ECO pressures: may save you an indeterminate amount of cash. However, due to decreased grip and increased braking distance you and/or your passengers may die horribly !

Mmm...

How safe is safe?...it’s not a word that appears anywhere in the owner manual ‘tyre pressure section’.

The crux of my question, and I still don’t  know the answer, is: would increasing the tyre pressures by 5psi on my daughters Volvo have any significant effect on stopping distances, given the same set of conditions?

It’s never going to be an exact science and I’m fully aware that pressures increase as the tyres get hotter but nonetheless I still think it’s a valid question.

My ECO caveat comment was tongue in cheek btw, but nonetheless with a serious undertone.

I might try a few experiments on my next track day.

I forgot to answer your question about the tyre fitter: as I stated upthread he had a Smart App apparently. I assumed, perhaps wrongly, the his App was Smart enough to  give him all the info that’s available on the cars  pressure info ‘sticker’.

He said that he was strictly forbidden to touch the doors or enter the vehicle in any way;...CV19 rules I assumed.

I don’t know how he arrived at a figure of 36psi but that’s what he put in. He was extremely large, dour and morose and looked thoroughly miserable as it had been lashing down all day,...so I didn’t query it. I’ve dodged a few spanners in my time and didn’t fancy dodging another one.

To be fair, he did carry out the job with some efficiency.

 

 

 

 

 

 

Well they aren't going to mention "safe" tyre pressures because then that would imply any tyre pressures not mentioned as safe are unsafe. All the pressure they specify are safe and they are would not be allowed to recommend pressures that were not safe. 

But you may find this interesting:

http://article.sapub.org/10.5923.j.ijtte.20130202.01.html

The conclusion was that the recommended pressure and 20% below offered similar stopping distances but 20% above noticeably increased the stopping distance. 
But don't forget underinflated tyres will provide worse lateral grip so a pressure near the middle of the recommended range would provide a good combination of both. 
You could fine tune this on a track day if you had suitable measuring equipment but not sure how effective this would be considering a change in conditions after you leave the track would change the results.

Thanks for that link;...I did find it interesting.