Tyre tread depth

[DonjSZ5]

Where did the minimum 1.6mm come from. Why not 1.5mm or 2mm.

 

Some authorities even say change them at 2mm and 3mm.

 

Is there a standard DoT for new tyres. 

 

Why don't manufacturers or retailers specify new tyre depths.

 

Food for thought.

[Dr Zoidberg]

Nearly all tyres come with 8mm tread to begin with and 1.6mm is where grip starts to tail off rapidly.

[steved83]

Some car manufacturers (BMW, Porsche, Mercedes for example) recommend changing at 3mm, as per hand book. Pretty sure Germany has a 3mm limit which is why a lot of premium brand tyres have two wear bars, one at 3mm one at 1.6mm.

Most tyre retailers and tyre manufactures will say 3mm too.

5mm tyre is 47% worn

4mm tyre is 62% worn

3mm tyre is 78% worn

2mm tyre is 94% worn

We change our fleet at 3mm

[Huskoda]

I follow the german 3mm guidelines, except with winters where I change at 4mm. 1.6mm is utterly ridiculous, especially for our wet climate. Trying to squeeze a few quid more out of old tyres is not worth the risk to me and my family.

Edited 10 February, 2016 by Huskoda

[giandougl]

Lots of new tyres these days have wear blocks in the tread areas, as a guide to minimum tread depth.

[mac11irl]

The german 3mm limit is why you see more than a few "indepently suspect" tyre places offering part worm premium brand tyres at knock down prices - they buy them from germany as waste and sell them on to people who dont overly care about the quality of the tyre or that its not going to be the same as a new set of the particular tyre theyve gotten..

[Brian69]

I change at 3mm - stuck four new tyres on last November and I've noticed the difference.

[SkodaTC]

My leasing company won't change tyres until they get below 2.0mm

[Pheasantplucker57]

Nokian Weatherproofs come with 7mm tread, not 8mm!

[Breezy_Pete]

1.6mm is very close to 1/16" (25.4/16 = 1.5875).

I bet that's where it comes from.  1/8" was probably deemed too wasteful, so that was the next 'common' division of an inch lower.

[keystonedriving]

Don't forget that for trucks, buses and motorcycles the minimum legal tread is 1mm, for mopeds it is 'visible tread'.

 

Something like 3mm is sensible, but as stated, some fleet lease companies don't like that idea.

[vrskeith]

Legal limit presumably set after studies undertaken by Department of Transport.

I would guess any accidents involving suspect tyre performance would have been picked up by insurance companies.However, I can understand that in certain areas of the UK that road condition/weather it may be more appropriate to change earlier or run winters .

Edited 10 February, 2016 by vrskeith

[Ootohere]

There has been a Landmark ruling in the Supreme Court on the case of a Home Care Worker that slipped on Ice while walking to a job.

It has been decided the Employers, a company that provides Carers for Glasgow City Council were negligent.

 

They had not provided the Employee with suitable Non Slip fitments to put on her shoes.

So now this ruling could affect all Employees UK wide.

 

http://bbc.co.uk/news/uk-scotland-glasgow-west-35540557

 

It should and might affect all Employers that have Employees Driving as part of their employment.

Ending those that Lease Cars and Vans and say that Winter Tyres are not needed, 

or that let vehicles continue to be used with tyres nearing the Legal Minimum tread depths.

 

I know it is a bit of a leap from personal shoes / footwear, but in practice really there is no difference, 

today in the Glasgow Area some of the vehicles sliding off the road should have stayed parked up, 

or the people driving should have walked and slipped to work until receiving training 

and a Common sense transfusion.

Edited 10 February, 2016 by GoneOffskiroottoot

[Nathanio]

1.6mm is very close to 1/16" (25.4/16 = 1.5875).

I bet that's where it comes from.  1/8" was probably deemed too wasteful, so that was the next 'common' division of an inch lower.

 

That's what I was thinking. A fall over from the imperial days

 

Some tyres noticably drop off under 4mm. Michelin PS3 and Toyo T1R (iirc) become very different once below 4mm. The PS3s wet weather performance took a serious nose dive when I used them. 

 

The GY F1A2s seem to last really well even down to 2mm. 

 

Some tyres are just crap regardless The Jinyu and Evergreen (on our Furby when we got it) were plain dangerous in damp let alone wet weather. Changed at 6mm and 7mm respectively!

[Dr Zoidberg]

That's what I was thinking. A fall over from the imperial days

 

 

 

But the legal limit was changed from 1mm about 20 years ago, and is a European standard, and they deal very much in Metric.

[Nathanio]

But the legal limit was changed from 1mm about 20 years ago, and is a European standard, and they deal very much in Metric.

 

Interesting - didn't know.  Thanks

[bealine]

I remember, years ago (probably about 1990-91), being treated to a tour of the Good Year tyre factory and seeing a couple of promotional films at the R&D department.    One of the films showed the dramatic deterioration of handling characteristics as the tyres wore beyond 4mm depth (they start at 8mm when new).  

All of us in the room expressed shock at the extra stopping distances required, especially in the wet (partially explained by the "sipes" having been worn away - "Sipes" are the little indentations, originally "S" shaped, that mop up water from the road surface leaving it dry for the 2 square inches of rubber compound actually in contact with the tarmac at any given moment.)   We asked the Good Year reps why this video wasn't released to the public domain - the response was "because we're a tyre manufacturer with a vested financial interest, no one would believe us!"   (Remember the "Monroe" shock absorber gaff when they said any car with 20,000 miles on the clock was sure to need all four shocks changing?   Tyre fitters all over Britain and America were changing shock absorbers like it was going out of fashion!)

It looks like RoSPA did its own research and the graph shows a very similar picture to the Good Year research, as well as 5th Gear.

https://www.youtube.com/watch?v=SdPMRMUbMuE

http://www.rospa.com/road-safety/advice/vehicles/tyre-safety-technology/tread-depth-wet-weather/

 

 

Edited 10 February, 2016 by bealine

[bealine]

This is the only point of contact between your car and the road, multiplied by four of course, but illustrates how reliant you are on having good tread in wet/icy conditions.   You can see the effect of water being sucked from the road at the front and spat out again  at the back of the tyre.

Edited 10 February, 2016 by bealine

[brad1.8T]

Where did the minimum 1.6mm come from. Why not 1.5mm or 2mm.

 

Some authorities even say change them at 2mm and 3mm.

 

Is there a standard DoT for new tyres. 

 

Why don't manufacturers or retailers specify new tyre depths.

 

Food for thought.

1.6mm is (near enough) 2/32".  The USA does tread depth in 1/32" increments (Goodyear does anyway).

 

At 2/32" you may as well not bother having tread for all the good it does. 

 

<3mm is the point where wet weather performance goes out the window.

 

I'm not sure what you mean by "Why don't manufacturers or retailers specify new tyre depths".  It's all available on the specification sheets and easily found

Edited 10 February, 2016 by brad1.8T

[DonjSZ5]

My recent purchase sparked me into this debate.

 

The car has traveled 29k miles and I like to know precisely what I am driving on so tyre inspection was my first port of call once I had it home for a full, wheel off, inspection. It's something you can only glance at when looking a car over during the buying process and in my case it was just to see if the wear rate was even and not showing signs of other factors that could affect the wear.

 

The front tyres were both fairly new with 6.5mm tread but of a make I have not heard of, Sunew YS618, and having Googled not a particularly popular one at that. I have yet to decide on their future but as I don't do a lot of high speed motoring and very few miles I suspect they will stay on but be moved to the rear once the rears have done a few more miles.

 

The rear tyres and spare are original Continental ContisportContact 5 and still have 5mm and 6.5mm of rubber respectively. These tyres have both 1.6mm and 3mm wear blocks. The wear is even and having covered the 29K miles I suspect a very good replacement once the time comes.

 

brad1.8T: I did look at the spec for a couple of brands but could not 'easily' find the as new depth. I also emailed Continental through their Q&A web page but have had no reply. Googling implied 8mm to 10mm being the norm. I assume the later more for the 4x4 fraternity. 

[Rustynuts]

My recent purchase sparked me into this debate.

 

The car has traveled 29k miles and I like to know precisely what I am driving on so tyre inspection was my first port of call once I had it home for a full, wheel off, inspection. It's something you can only glance at when looking a car over during the buying process and in my case it was just to see if the wear rate was even and not showing signs of other factors that could affect the wear.

 

The front tyres were both fairly new with 6.5mm tread but of a make I have not heard of, Sunew YS618, and having Googled not a particularly popular one at that. I have yet to decide on their future but as I don't do a lot of high speed motoring and very few miles I suspect they will stay on but be moved to the rear once the rears have done a few more miles.

 

The rear tyres and spare are original Continental ContisportContact 5 and still have 5mm and 6.5mm of rubber respectively. These tyres have both 1.6mm and 3mm wear blocks. The wear is even and having covered the 29K miles I suspect a very good replacement once the time comes.

 

brad1.8T: I did look at the spec for a couple of brands but could not 'easily' find the as new depth. I also emailed Continental through their Q&A web page but have had no reply. Googling implied 8mm to 10mm being the norm. I assume the later more for the 4x4 fraternity. 

 

I doubt very much that at 29k miles your rear tyres are original with +5mm tread depth. When I mistakenly bought Continentals thinking they were a reasonable bargain against Michelins, they were scrap after 10k miles.

[Nathanio]

My recent purchase sparked me into this debate.

 

The car has traveled 29k miles and I like to know precisely what I am driving on so tyre inspection was my first port of call once I had it home for a full, wheel off, inspection. It's something you can only glance at when looking a car over during the buying process and in my case it was just to see if the wear rate was even and not showing signs of other factors that could affect the wear.

 

The front tyres were both fairly new with 6.5mm tread but of a make I have not heard of, Sunew YS618, and having Googled not a particularly popular one at that. I have yet to decide on their future but as I don't do a lot of high speed motoring and very few miles I suspect they will stay on but be moved to the rear once the rears have done a few more miles.

 

The rear tyres and spare are original Continental ContisportContact 5 and still have 5mm and 6.5mm of rubber respectively. These tyres have both 1.6mm and 3mm wear blocks. The wear is even and having covered the 29K miles I suspect a very good replacement once the time comes.

 

brad1.8T: I did look at the spec for a couple of brands but could not 'easily' find the as new depth. I also emailed Continental through their Q&A web page but have had no reply. Googling implied 8mm to 10mm being the norm. I assume the later more for the 4x4 fraternity. 

 

 

Having had some ditchfinders recently; I found them dangerous and did not want to take the risk of an accident over saving £200. My Excess is £150 on our cars so almost as much as a set of tyres. If I'd had an accident because I couldn't stop in time, then it cost a lot more than a set of tyres. I changed at 6 and 7mm due to the fact I had understeer and oversteer in a 15mph damp corner. 

[mdon]

Most police forces policy is 3mm ours certainly is. On my own car I generally change between 2-3mm.

[skinnyman]

The front tyres were both fairly new with 6.5mm tread but of a make I have not heard of, Sunew YS618, and having Googled not a particularly popular one at that. I have yet to decide on their future but as I don't do a lot of high speed motoring and very few miles I suspect they will stay on but be moved to the rear once the rears have done a few more miles.

 

I've just broken out in a cold sweat reading that part! Please don't put them on the rear when you get new tyres, just get rid and put a decent set on regardless of how much tread they have left. 

 

I say this because I care.

 

https://www.youtube.com/watch?v=__0DL8dE3Eo

 

http://kumhotyre.co.uk/kumho-news/should-you-fit-new-tyres-to-the-front-or-rear/

 

https://www.youtube.com/watch?v=oa9hzcjdi5Q

Edited 11 February, 2016 by skinnyman

[logiclee]

Had 4 new tyres on the Octy today, (Cross Climates) 

 

Fronts were down to 3mm and one had a slow puncture, couldn't see the point in getting it fixed. Rears had 4mm left but didn't want to mix the cross climates with summers.