Strange Tyre Treads

Wig

My car is fitted with a single ZETI ZTR20 M&S not bought my me I might add.

I will first describe two types of tyre tread found on most tyres

Type 1: These are the main 'canyon' treads which are in the central 3/4 of the tyre they are somtimes straight and go all the way round the circumference of the tyre continuously. We shall call these lateral treads

Type 2: are like little 'tributaries' which run from the tyre wall into the canyons, we shall call these radial treads.

On this particular tyre the lateral treads have the TWIs and there is about 3mm or more left on the lateral treads so the TWIs are still well below the tyre surface.

I noticed that the radial treads were much more shallow almost on the limit. This needed to be investigated. So upon closer examination, I discover that the radial treads join the lateral threads half way up the valley wall at approx the height of the TWIs like "hanging valeys" from your geography lessons. Which means the tyres will be illegal long before the TWIs are reached.

I examined the other tyres (different brands) on the car and sure enough on all the other 4 tyres (spare ) The radial treads have the same depth as the lateral treads, meaning the valley floor of the radials meet with the valley floor of the laterals. Meaning the treads will become illegal only when the TWIs are reached.

How crazy is this tyre design? Made me think, next time I buy tyres, I'm going to have to check this feature before I buy.

Hammyman

Are you sure its not worn like that due to incorrect tyre pressure?

Wig

Absolutely positive, because the radial treads join the lateral treads like hanging valleys, which proves they had less tread depth to begin with.

Paradigm

I'm certainly not a tyre design expert but I think it's related to speeding up water flow?

The lateral tread(s) collect the water & it's then forced into the shallower radial treads, to move the same amount through a narrower channel it must travel faster & is literally "squirted" away from the tyre!

As nearly all tyres are the same that's my take on it but I could (most likely am) be wrong

This tyre however seems to break all the rules.......

daveyjp

M&S are mud and snow tyres and should be replaced before the TWI are reached anyway.

maninthestreet

daveyjp wrote: »

M&S are mud and snow tyres and should be replaced before the TWI are reached anyway.

Marks and Spencers make tyres now????

:D:D

Wig

daveyjp wrote: »

M&S are mud and snow tyres and should be replaced before the TWI are reached anyway.

They don't have to be, especially if you want to use them through summer to use up the remaining legal tread wear. And other M&S designs have radial and lateral tread of the same depth.

I think I like Pardigm's idea which may be why they did this. but as I haven't seen any other tyre like this, one can only assume it was a bad idea. And the effect of this when new is going to be minimal (see picture below)

You can see the tyres here exactly the same <removed dead link>
And you can see there is a shadow at the end of the radial treads showing there is a difference in height of tread depth. You can also see that these "M&S" don't have the traditional micro-treads that most other M&S tyres have so not really M&S tyres?

Paradigm

Wig wrote: »

I think I like Pardigm's idea which may be why they did this. but as I haven't seen any other tyre like this,

I like my idea as well, doesn't mean it's right though

If you look at most tyres the radial tread narrows towards the edge of the tyre... just been out & looked at my daughters Clio & they are the same becoming less deep & less wide as they reach the outer edge.

Maybe we need Mr Michelin to expain it to us