"Siping"

[L.W. Baxter]

Just got four new light truck tires this morning, the salesman was pushing hard for me to pay for "performance siping", wherein the treads are slashed diagonally every half inch or so to, supposedly, increase traction and keep the tread cooler.

I'd never heard of it, and it seems preposterous. But they've got a glossy brochure illustrating all the benefits, and also a tepid explanation as to why the tire manufacturers don't do the siping themselves ("because it costs too much"LOL).

Anyway, the really annoying part was, when I declined to pay an extra 12 bucks a tire to have them sliced up, the salesman gave me the downcast-eyes-dismissive-shrug-some-people-you-just-can't-reach look.

So what do we think? Does siping improve tire performance and durability, or is it a scam?

[Bruce Hooke]

This PDF (http://www.goodyear.com/truck/pdf/radialretserv/Retread_S12_V.pdf) from Goodyear seems to offer a detailed rundown of the risks and benefits of the practice...

[Ross M]

Preposterous, IMO. A key factor in tire wear (particularly early in the tire's life) is tread squirm; where the tread blocks move around causing unnecessary abrasion.

I would suspect that this treatment exacerbates tread squirm, possibly dramatically.

To me, there are two kinds of wet weather performance:

a) Traction - how well the tread compound develops friction against a wet surface; determined largely by compound, age and interface temperature

b) Hydroplaning Resistance - how well the tire evacuates water from the interface. Controlled largely by tread pattern and remaining depth.

I can imagine that the siping may well improve a) for a short period of time - simply by increasing the interface temperature. But it is almost bound to reduce tread depth prematurely, reducing the hydroplaning resistance significantly.

YMMV

Ross

[L.W. Baxter]

From the link Bruce provided:



Tire siping is a process of making
small knife-like slits in the tread rubber
surface. Normally this is accomplished
by a machine that uses sharp, highspeed
rotating discs to make cuts that are at an
angle of 90° to the circumference of the
tread. Siping cuts are normally controlled
so they are spaced a specific distance
apart from one another. They also will
vary in depth across the tread face.

Proponents of tread siping have claimed
various performance improvements for
truck tires. These claims include improved
treadwear and reduced irregular wear.
Also, it is often claimed that siping
improves traction for winter and wet
driving conditions on certain road types.
At present, the majority of truck tire
siping is done in the westernmost
Midwest states and the Northwest
corridor. It is popular in certain areas,
and especially during the winter months,
to sipe both steer and drive, and
sometimes trailer tires.

Goodyear’s position on siping is that
it may, under certain operating conditions,
improve tire performance. However,
under the vast majority of truck operating
conditions, new tires are designed and
produced with tread patterns and tread
compounds that do not require tread
siping to give satisfactory performance.
Actual testing indicates that siping
may improve the tire’s resistance to
irregular wear on free-rolling wheel
positions that are susceptible to irregular
wear due to the combination of operating
service and tire application. Specifically,
siping may help reduce irregular wear
on trailer axles where light, one-way
loads are encountered, such as grain
trailers or belly dumps that operate
under extreme load variations from
unloaded to loaded conditions.

On the other hand, siping is generally
believed to detract from treadwear on lug
type tires used on drive-wheel position.
This is because siping tends to break up
the tread pattern and cause increased
bending of the tread elements. This
results in faster wear due to increased
scuffing as the tire goes through its
footprint under torque.

The effect tread siping has on tire
performance can vary considerably with
the particular tire pattern being siped.
For example, in a heavily bladed tread
pattern it is believed that siping in the
original tread state could hurt treadwear.
Other tread patterns, such as those
having a much higher net-to-gross
footprint area, might be more adaptable
for siping under the service conditions
discussed earlier.

If a customer chooses to sipe his
Goodyear tires, we strongly recommend
that he pay close attention to the type of
siping used. Specifically, our experience
is that siping should be performed laterally
across the tread, although angles that
vary somewhat from this might also be
acceptable. However, to the best of our
knowledge, siping that is more or less
circumferential has not been demonstrated
to be successful. Also, our experience
shows that siping with varying depth
across the face of the tread usually
yields better results than constant depth
siping. This also appears to provide the
minimum risk for increasing the tire’s
susceptibility to tread rubber chunking.

It is important to note that the
Goodyear warranty provides protection
for the user against failures from
workmanship or material conditions.
If a tire failure occurs because of a
condition beyond Goodyear’s control,
such as siping, the warranty is null
and void.
Definitely a mixed bag, with no clear benefits.

I'm really disappointed with my tire store. Ten years ago they were fabulous, service oriented, no B.S. Now, every time I go in there, they're trying to sell me something extra.

On a different vehicle last year, it was brake pads, which they claimed were at 10% and which they could change for me. I ignored them, drove another ~5k miles, then checked in with my regular mechanic, who told me my pads were at about 20%, come back in another 10k miles.

[Paul Scheuer]

If a tire failure occurs because of a
condition beyond Goodyear’s control,
such as siping, the warranty is null
and voidWhen it doesn't make sense, Follow the money.

[htom]

Sometimes it helps and sometimes it doesn't and mostly I can't tell, so I don't do it any more. I suspect that there is probably a way to improve traction from a tire, but there are so many variables in siping (depth, angles, length of cuts, density, spacings, ...) that only a manufacturer could do the testing to find out which, and then you'd have to apply that to real roads and cars and drivers ... not gonna happen.

You're better off to spend an extra twelve dollars on each tire buying a better tire, if there's one available.

[Ron Williamson]

Factory siping is done on winter tires all the time.I think the prime advantage is on ice.Think boat shoe soles,they're exactly the same.
I don't see the point of aftermarket siping for properly designed tires.
R

[NormMessinger]

My Brigestone Blizack tires are almost as good as tire chains in ice and snow. Apparentlly Oreogon and California, at least, allow them in lieu of required chains.