Tyre Treads and rotation direction

Makhaira · 26 Dec 2012 at 22:48

Ok, so this isn't quite a "do they need to rotate a certain way" thread, since as far as I'm aware, the answer is "no". My question is more "why?".

I'll do my usual 6 monthly rotation of my AS2's soon, doing diagonal swaps all around to even up wear. This of course means that the tyres will now rotate the other way. Given that the tread pattern is effectively reversed then, why is there not an optimal direction for these tyres? Is there black magic at work such that the difference is negligible?

This is what happens when you drink on Boxing Day and then think about car tyres....

Finglonga · 26 Dec 2012 at 22:57

The tyre is designed to optimise the clearance of water, by reversing the tread pattern you could well be causing it to push water under the tyre instead of away. Not 100% sure but I think it is also a MOT failure.

PhillyDee · 26 Dec 2012 at 23:45

If they have a direction on them, then yes, they need to go the correct way. For the reason above.

The1nonly1 · 27 Dec 2012 at 00:13

ask a garage to swap them around for you?

Simon · 27 Dec 2012 at 00:25

Assymetrics will have inner or outer rather than direction.

Makhaira · 27 Dec 2012 at 05:39

Simon said:
Assymetrics will have inner or outer rather than direction.

Exactly, that's what baffles me!

Dogbreath · 27 Dec 2012 at 08:58

Makhaira said:
I'll do my usual 6 monthly rotation of my AS2's soon, doing diagonal swaps all around to even up wear. This of course means that the tyres will now rotate the other way. Given that the tread pattern is effectively reversed then, why is there not an optimal direction for these tyres? Is there black magic at work such that the difference is negligible?

No black magic, the tyres are simply designed to work effectively in both directions. Isn't this pretty obvious?

Simon · 27 Dec 2012 at 09:36

Makhaira said:
Exactly, that's what baffles me!

Well they will always stay as the outer part of the tyre. So no issue, just give them time to bed in

namnoc · 27 Dec 2012 at 12:35

If they were designed to be bad going the wrong way then losing grip in reverse would be too easy and any one could do a decent J-turn

PhillyDee · 27 Dec 2012 at 13:39

namnoc said:
If they were designed to be bad going the wrong way then losing grip in reverse would be too easy and any one could do a decent J-turn

Think 'less effective' than 'bad'

Finglonga · 27 Dec 2012 at 14:33

Makhaira said:
Exactly, that's what baffles me!

They usually go on performance cars that have a slight camber so my guess is the inner has a harder compound so the width wears at an even rate.

bledd · 27 Dec 2012 at 15:00

Directional tyres have an arrow saying which way they should rotate

Asymmetric tyres have 'outer' on them (outer edge of the wheel)

Makhaira · 27 Dec 2012 at 16:23

Understand the fact that they have the "sides" marked and other than that it doesn't matter, it's more a case of "why" it doesn't matter. As PhillyDee said, surely there must be a difference since the tread rotates in a different direction? I believe that only the sides matter, hence why I'm swapping diagonally, it's just the "why" that is beyond me!

Dogbreath · 28 Dec 2012 at 07:32

Makhaira said:
it's just the "why" that is beyond me!

It's obvious if you look at the tread pattern; the diagonal cuts on the inside half of the tread are at a very shallow angle and the angle is primarily to reduce road noise rather than to aid water dispersion (a straight cut would mean numerous tread blocks would be meeting or leaving the contact patch at the same time). With such a shallow angle any difference in performance through water between opposite rotations is going to be negligible.

Makhaira · 28 Dec 2012 at 10:14

Thank you