AHAR meaning: the rubber Asics puts where the sole wears

What the compound is made of

Asics’s own description of the material is short and unusually concrete. Abrasion resistance, it says, “has been improved by using a rubber material that is also used for car tires which require high durability as the main material for the outer sole, and mixing it with a reinforcing material”.

That is a statement about what the stuff is, and it is rarer than it sounds. Most outsole rubber is described by what it achieves – grip, durability, confidence underfoot – rather than by what went into it. Here the claim is checkable in principle: tyre-grade compound, plus a filler to reinforce it.

There is a second form. Asics states that a sponge version of the same material “has realized a more than 50% reduction in weight compared to our conventional products”. That is the version that turns up where a sole needs to last without weighing anything, and it is the quieter half of the story – the interesting trade here is not grip against durability but durability against grams.

What the figures compare with

One sentence carries the whole marketing case, and it is worth reading slowly:

• AHAR has an abrasion resistance about two times higher, and AHARPLUS about three times higher, than “our conventional rubber”

The last four words are the ones that matter, and they are almost always dropped by the time the figure reaches a product page. Twice as durable as what? Asics does not name the conventional rubber, does not date it, and does not say whether it is still used in anything. The comparison is with the company’s own earlier material, not with anybody else’s.

Nor is there a method. No test standard is named, no abrasion rig, no laboratory, no sample size. “About two times” is a figure with an “about” in front of it and nothing behind it. That does not make it false. It makes it unarguable, which is a different problem: you cannot repeat a measurement that was never described, and you cannot compare it with a rival’s figure that was measured some other way.

What the claim does tell you honestly is the shape of the design. Asics set out to make its outsole last longer than its own previous one, and says it roughly doubled it. That is a real engineering goal and a plausible result. It is simply not a number you can carry across to another brand’s sole.

The two names, and the page that is gone

Here is the oddity. Everything quoted above comes from Asics’s own technical page for the material – and that page never expands the acronym. It writes AHAR and AHARPLUS, and leaves the letters alone.

Two expansions circulate. Retailers and Asics’s own consumer blog give Asics High Abrasion Resistance Rubber. Elsewhere, including in coverage that cites Asics, it appears as Asics High Abrasion Rubber. Both are in use, the brand has published the first, and the technical page settles neither. If you have seen the two versions and assumed one of them was a typo, it was not.

The page itself is the second oddity: it is no longer on the Asics corporate site, and the address returns a 404. The quotations here were read from an archived capture of it taken on 7 February 2018. The material is still in the shoes and still named on the boxes; the explanation of it has quietly gone. That is most of the reason there is so little to read about AHAR anywhere: the primary source stopped being served.

Where you’ll find it

Asics names AHAR across much of its range, so this will fill in as the table grows. The one shoe here that carried it, the Novablast 4, is now in the archive.

When it matters, and when it does not

It matters if you wear heels out. Some runners land hard enough on the outside of the heel to scrub through an outsole before anything else on the shoe is finished, and for them the AHARPLUS plug under that corner is the difference between retiring a shoe at four hundred miles and at six. If you have ever looked at a pair and seen the tread gone in one patch and perfect everywhere else, you are that runner.

It matters much less for everybody else, because most running shoes do not die of a worn outsole. They die of a midsole that has stopped bouncing back, somewhere between 310 and 500 miles, while the tread still looks usable. A sole twice as hard-wearing does nothing about that. It extends the life of the part that was not going to fail first.

And it is not a grip claim. Hard rubber is the opposite of grippy rubber, which is exactly why Asics puts it only in patches and leaves softer compound in between. On a wet road the part of the sole doing the gripping is the part that is not AHAR.

Similar and competing technologies

Every brand has a hard-wearing outsole rubber and a name for it. What separates them is not the compound, which nobody publishes, but who made it and what the claim is measured against.

The pattern is worth carrying to the next shoe you look at: an outsole figure is almost always a multiple of the same maker’s previous rubber, and almost never a measurement you could repeat. The other outsole technologies are the same story under different names.