Minimum thread depths

corklad32

Hi Guys,

I'm looking at my thread wear indicators on my car tyres. I noticed that there's two different sets of indicators one at a lower level than the other. Anyone any idea what the lower / higher one relates to?

Swordfish01

corklad32 wrote: »

Hi Guys,

I'm looking at my thread wear indicators on my car tyres. I noticed that there's two different sets of indicators one at a lower level than the other. Anyone any idea what the lower / higher one relates to?

Without seeing the tyre its difficult to know is there any chance that you could be looking at two indicators on either the inside and outside and one has more thread than the other which means the tyre is wearing un even???

coylemj

I'm the same, Bridgestones on a VW Golf. I've searched high and low but nobody mentions two different depths of tread wear indicator. On your car the probability is that the lower indicator is the legal minimum 1.6mm.

There was a brief thread on this topic last year but it got no meaningful answer to the main question which was the same as the one you are asking..

http://www.boards.ie/vbulletin/showthread.php?t=2055968765

Don't expect to get an intelligent answer from the local tyre chain shops, I went to two of the more prominent branches in Dublin a couple of years ago, not alone could they not quote the legal definition of the minimum tread, neither of them even had a tread depth gauge. They just tell everyone who comes in that their tyres are worn out and gullible that they are (for not asking the guy to define the legal minimum), they cough up and buy new tyres.

coylemj

Swordfish01 wrote: »

Without seeing the tyre its difficult to know is there any chance that you could be looking at two indicators on either the inside and outside and one has more thread than the other which means the tyre is wearing un even???

If he's got the same indicators as me, they are of mixed height but sitting in the same groove so could not be caused by uneven wear.

Gary ITR

I've seen this before and been told that the higher one when manufacturer recommends replacing and the lower being the legal minimum. Do yourself a favour though and measure them to see if they are above or below the legal limit

peasant

As has been said, the legal minimum is 1.6 mm.
The tyre industry keeps pushing a thread depth of 4 mm as a minimum for wet handling (that has actually been proven by several independent tests)

Your tyres probably have marker at 4mm and 1.6 mm.

Considering that we live in a pretty moist country (and finances allowing) I would contemplate changing tyres above the legal limit.

Personally, I always buy new tyres once they are down to around four mm or below.

-Corkie-

What mm of thread is on a brand new tyre so?

peasant

Depends on the tyre, could be from 6 to 8 mm.
Some commercial or winter tyres even have 10 mm

peasant

Aquaplaning:

https://www.youtube.com/watch?v=2DgtRHZPRm4

-Corkie-

peasant wrote: »

Depends on the tyre, could be from 6 to 8 mm.
Some commercial or winter tyres even have 10 mm

I was thinking 6mm. If you change them at 4mm they must last no time at all???

Paddy001

Without seeing them I cant say, but with the bridgestone I'm pretty sure what you have is a higher marker at 1.6mm and a lower one which I believe is 1mm, this is the legal limit for vintage vehicles and probably the legal limit in some other countries. Some tyres have higher markers which are obviously what the manufacturer reccommends, but these are rarer

I've seen NCT warning on test reports with tyre depth below 3mm. 1.6mm is not much at all.

coylemj

I have the Bridgestone tread depth gauge, I'll measure the depth tomorrow down to each of the two markers and see what they read. I know there's 3mm overall depth to the bottom of the grooves.

gofaster_s13

3mm is the legal winter wear limit in a lot of countries and 1.6mm is the legal wear limit for the rest of the year(or all year limit in some countries), this is usually the reason for two different tread wear indicators.

Nissan doctor

3mm is the recommended safety limit for road legal car tyres and 1.6mm is the legal minimum limit.

All new car tyres have the wear indicators for the minimum legal limit. The OP has not replied with what sort of tyres he has as 4x4 tyres have 2 indicators, one for off road traction limit(usually approx 4mm) and one for the legal road limit.