MOT advisories: Tyre worn close to legal limit

AdrianC

jimbo6977 said:

Please also buy 2 tyres - left and right. Much safer. 

...and pay the tiny amount more for decent-brand tyres, not off-brand Chinese teflon/concrete rubbish.

Tell us what size they are, we'll point you to some decent alternatives.

onomatopoeia99

DiddyDavies said:

lesalanos said:

Tyres are made to perform at a safe standard down to the minimum legal tread depth.

Due to the reduced movement of the tread blocks tyres run more efficiently when lower in tread.   Replacing tyres early is a financial and environmental cost.  

Define "safe standard"? 
Once tyre tread gets to about 4mm, there is a marked decline in their ability to grip the road which is why stopping distances increase dramatically from this point:
Tyre Tread Depth and Stopping Distances (rospa.com)

That graph was produced by MIRA, (an independent company with no affiliation to any tyre manufacturers).
I know that the speed of the test vehicle isn't shown but whatever speed it was, the stopping distance is increased a fair bit long before the 1.6mm minimum tread limit is reached.

As to the environmental cost of replacing tyres.
Once a tyre has been manufactured, there is a set amount of rubber that will need to be disposed of at some point and whether it's when the tread has reached 1.6mm or 4mm, that figure will be the same.
The only difference between a tyre at 1.6mm and one at 4mm is that on the 1st one,  2.4mm of rubber has already been removed through driving but that worn away rubber is still in the environment somewhere. It hasn't simply disappeared.

The report doesn't state that the tyres used for the different tread depth tests were the same brand, type and age, which they need to be for the data to have any meaning.  It doesn't test against multiple brands at the same tread depths so the performance of the tyres used can be demonstrated not to be an outlier.  Aside from a picture of a car on a wet road, it doesn't even state that the test was done in wet conditions, nor how wet.  It also doesn't do a comparative test using the same tyres on a dry road (which would show a completely different graph).

As a piece of research it's lacking, either in the data collected or the way it is presented.

Marvel1

Treat it as it is, an advisory, and keep checking.

daveyjp

The testing was done 17 years ago, so is certainly due an update with more modern tyres.

However I know from personal experience that once tyres get to 2- 2.5mm the handling can affected.  Damp roundabouts can become 'interesting'.

qsk

Thanks all for the comments. It is an interesting and educational discussion from both sides of arguments. Some more information: the tyre in question is a Michelin Energy Saver 205/55R16V (91), about 2 to 3 years old. The garage is ATS. I am not a heavy driver - usually 10000 miles a year but only 8200miles in last 18 months due to work from home. 

Car_54

jimbo6977 said:

Please also buy 2 tyres - left and right. Much safer. 

Have you any evidence that it's "much safer"?

AdrianC

qsk said:

Thanks all for the comments. It is an interesting and educational discussion from both sides of arguments. Some more information: the tyre in question is a Michelin Energy Saver 205/55R16V (91), about 2 to 3 years old. The garage is ATS. I am not a heavy driver - usually 10000 miles a year but only 8200miles in last 18 months due to work from home. 

How even is the wear across the tread?

https://www.blackcircles.com/order/tyres/search?width=205&profile=55&rim=16&id=10044
If price is most important to you, those £55 Avons are bargainacious.
If poor-weather grip is important to you, the £64 Uniroyal RainSports
If you get hard winters, the £84 Mich CrossClimates are worth every penny of the extra.

Biggus_Dickus

onomatopoeia99 said:

DiddyDavies said:

lesalanos said:

Tyres are made to perform at a safe standard down to the minimum legal tread depth.

Due to the reduced movement of the tread blocks tyres run more efficiently when lower in tread.   Replacing tyres early is a financial and environmental cost.  

Define "safe standard"? 
Once tyre tread gets to about 4mm, there is a marked decline in their ability to grip the road which is why stopping distances increase dramatically from this point:
Tyre Tread Depth and Stopping Distances (rospa.com)

That graph was produced by MIRA, (an independent company with no affiliation to any tyre manufacturers).
I know that the speed of the test vehicle isn't shown but whatever speed it was, the stopping distance is increased a fair bit long before the 1.6mm minimum tread limit is reached.

As to the environmental cost of replacing tyres.
Once a tyre has been manufactured, there is a set amount of rubber that will need to be disposed of at some point and whether it's when the tread has reached 1.6mm or 4mm, that figure will be the same.
The only difference between a tyre at 1.6mm and one at 4mm is that on the 1st one,  2.4mm of rubber has already been removed through driving but that worn away rubber is still in the environment somewhere. It hasn't simply disappeared.

The report doesn't state that the tyres used for the different tread depth tests were the same brand, type and age, which they need to be for the data to have any meaning.  It doesn't test against multiple brands at the same tread depths so the performance of the tyres used can be demonstrated not to be an outlier.  Aside from a picture of a car on a wet road, it doesn't even state that the test was done in wet conditions, nor how wet.  It also doesn't do a comparative test using the same tyres on a dry road (which would show a completely different graph).

As a piece of research it's lacking, either in the data collected or the way it is presented.

 I’ve no idea when this “3mm Tread” site was launched but tyre industry giant Michelin apparently hit-back at their campaign to change UK tyre legislation.

http://www.3mmtyres.co.uk/index.aspx

http://www.transportengineer.org.uk/transport-engineer-news/michelin-hits-back-at-3mm-car-tyre-change-campaign-updated/155431

Do we change our tyres at 3mm....1.6mm.... somewhere between?

What’s a guy to do‽

¯\_( ツ)_/¯

 

 

ontheroad1970

Tiexen said:

Michelin says: “ Modern tyre technology makes it possible to provide high levels of performance and grip from new, and through all of the tyre’s life down to the legal tread wear limit.

“With this in mind, changing tyres early (i.e. before they are fully worn) does not guarantee greater safety, and no current studies have established a direct link between accident levels and tyre tread depth. Suggesting that tyres need to be changed early (before the legal limit / tread wear indicator is reached) is akin to enforcing a form of planned obsolescence.

“Changing tyres too early would result in 128 million additional tyres being used a year in Europe - which would cause nine million tons of additional CO2 emissions every year. In addition to the environmental impact, replacing tyres before they are fully worn also represents a significant and unjustified increase in costs for consumers

As tyre tread depth reduces, the fuel economy of the vehicle will improve, and with one tank of fuel in five being used to simply overcome the rolling resistance of the vehicles tyres, this is a welcome benefit. The rolling resistance of a tyre at the point of removal at the legal tread limit is 80 per cent of that tyre in a new state. Therefore, keeping a tyre on the vehicle until the legal tread wear limit increases the time when it is in its most fuel efficient state, and reduces the motorist’s fuel bill.

on wet roads, some worn tyres can perform as well as some new tyres, and that although the remaining tread depth is a factor in wet braking, the performance of the tyre, at all stages of its life, is more important.

It adds: “Whilst all tyres legally sold in Europe meet this minimum standard when new, Michelin tests have shown that the wet braking capabilities of some tyres reduce quickly when worn, and may fall below this ‘minimum standard’ requirement. However, some premium products not only meet the criteria when new, they do so when worn to the legal tread wear limit.

I recently changed my tyres from Toyo Summer tyres to Bridgestone All Season (19 inch).  It's definitely impacted my fuel economy.

Car_54

ontheroad1970 said:

Tiexen said:

Michelin says: “ Modern tyre technology makes it possible to provide high levels of performance and grip from new, and through all of the tyre’s life down to the legal tread wear limit.

“With this in mind, changing tyres early (i.e. before they are fully worn) does not guarantee greater safety, and no current studies have established a direct link between accident levels and tyre tread depth. Suggesting that tyres need to be changed early (before the legal limit / tread wear indicator is reached) is akin to enforcing a form of planned obsolescence.

“Changing tyres too early would result in 128 million additional tyres being used a year in Europe - which would cause nine million tons of additional CO2 emissions every year. In addition to the environmental impact, replacing tyres before they are fully worn also represents a significant and unjustified increase in costs for consumers

As tyre tread depth reduces, the fuel economy of the vehicle will improve, and with one tank of fuel in five being used to simply overcome the rolling resistance of the vehicles tyres, this is a welcome benefit. The rolling resistance of a tyre at the point of removal at the legal tread limit is 80 per cent of that tyre in a new state. Therefore, keeping a tyre on the vehicle until the legal tread wear limit increases the time when it is in its most fuel efficient state, and reduces the motorist’s fuel bill.

on wet roads, some worn tyres can perform as well as some new tyres, and that although the remaining tread depth is a factor in wet braking, the performance of the tyre, at all stages of its life, is more important.

It adds: “Whilst all tyres legally sold in Europe meet this minimum standard when new, Michelin tests have shown that the wet braking capabilities of some tyres reduce quickly when worn, and may fall below this ‘minimum standard’ requirement. However, some premium products not only meet the criteria when new, they do so when worn to the legal tread wear limit.

I recently changed my tyres from Toyo Summer tyres to Bridgestone All Season (19 inch).  It's definitely impacted my fuel economy.

Impacted? For better or worse?