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Green Diamond Tires have a unique, patented technology which embeds silicon carbide particles into the tread rubber. Silicon carbide, also known as carborundum, is one of the hardest materials known (9.5 on the Mohs scale, where diamond is 10). It is commonly used on saw blades and abrasives. In a tire, the embedded particles provide grip on icy surfaces.

The technology was invented in Iceland, and Green Diamond is popular in Scandinavia. US production started in 1999. Green Diamonds are “remolded” tires. They begin with a worn-out major-brand radial tire, remove the remaining tread, inspect for internal damage, and then apply the new tread using a specialized press. One benefit is that tires are kept out of landfills, reducing the use of crude oil to make new synthetic rubber.

Remolding is claimed to be stronger than traditional retreading. The Icelander rubber wraps about 2/3 of the way around the sidewall, in addition to the tread, so it seems to have a lot of material attached to the original tire. I've driven mine through two winters, including highway driving, and I've not seen or felt anything that appears weak.

To protect the manufacturing equipment, Green Diamond tires have a thin veneer of ungranulated tread rubber molded over the granules, which wears off in use. In order to get the benefits for winter driving, the tires must be “run-in” by driving 1,500 to 2,000 miles on clear, dry roads. I didn't appreciate the significance of this, and installed the new tires on my '91 Miata in December 2007. They were pretty slick in the first snow and really didn't impress me all winter.

This winter, the tires have performed excellently. The “run-in” made all the difference. I don't hesitate to drive on snowcovered roads, even up inclines. Braking is sure and consistent. In Chicago, our roads don't stay snow-covered very long, they get plowed and salted. The Icelanders are pretty good on dry surfaces, but are easy to spin accelerating on wet pavement (about the same as Falken Azenis summer tires). Based on the remaining tread, I'm expecting at least five more winters from these tires.

By comparison, I've previously driven an early version of the Bridgestone Blizzak (WS-15) on my Miata, and I'd say the Icelanders are as good or better on snow and ice, and much better on dry pavement. I've also driven Michelin Arctic Alpins on an MX-6. Those were the best winter tires I've owned, with great snow traction and excellent performance on wet and dry surfaces. Unfortunately, the Arctic Alpin has been discontinued.

Bottom line: Would I buy Green Diamond Icelanders again? Yes, but I'd make sure to mount them in October, so I could “run-in” the rubber before winter. Also, it would depend on the price. Green Diamond doesn't have any dealers in our area, so you have to buy them online at www.greendiamondtire.com. Currently, Miata-sized tires (185/65R14) are $77.95 each, plus shipping. For comparison, www.tirerack.com has the Bridgestone Blizzak WS-60 (185/70R14) for $72.00 and Michelin's X-Ice Xi2 (185/65R14) for $80.00. For the extra two dollars, I'd probably go with the Michelins.
Kenton Andersen

tires