Long-Termer: Dunlop’s Latest

Good news for our Mazda BT-50 long-termer is that it has just been fitted with a set of Dunlop’s Grandtrek AT3G tyres.

We fitted a set of LT 265/65 R17 tyres which have a load rating of 120 (1400kg per tyre), and an “R” speed rating (170km/h). Pricing per tyre at this stage should be around R3000, ex Vat and fitment.

Why would we change tyres? Simple, really. The AT3G, unlike a number of other all-terrain tyres on the market, has a three-ply sidewall design; and from the get-go, it looks to be the business as aftermarket fitment for tough applications. The sidewalls are beefy and substantial (see image). I was able to compare them off-rim with a range of other all-terrain tyres at the Dunlop Zone down the road in Tokai where we had them fitted, and was surprised at how thick they were. The tyres themselves are heavy – at 18kg, more than a kilo heavier than the Mazda’s standard fitment Dunlop Grandtrek AT22s. That extra mass is all extra plies and more rubber. In other words, this is a properly constructed LT (Light Truck) tyre, rather than the more highway-oriented AT22s.

What’s more, we had all the tyres perfectly balanced using the high-tech machine at the Tokai Dunlop Zone fitment centre. This machine allows accurate spinning of the tyres against a rolling road, accounting for and dealing with those minor variations that are inevitable in rim building and tyre construction. Extra weights within a much smaller range are placed exactly where they are meant to be, pinpointed by a laser line on the rim. This service is a small add-on cost when you buy a new set, but will add nearly R1000 to the bill of a customer who wants to troubleshoot a ride problem – and this can be done, even if it takes deflation and rebeading, or swapping tyres to alternative rims, to sort out the problem.

Balancing done, what about the ride? Well, it feels as comfortable as before. Highway noise levels are just about on par, but this is a hard thing to evaluate. What we like about this tyre is multi-fold. First, it has a high load rating: 120, meaning 1400kg per wheel – and higher than the 112 of the AT22s. That means we can load the Mazda or tow a heavy trailer with more peace of mind. Second, it has a chunky and aggressive tread pattern with a decent tread depth of 11.3mm: not only should it provide a long tread life, but should do the important job of self-cleaning well in muddy conditions, and provide ample grip on gravel. Third, those tough sidewalls are a boon when off-roading: offering more peace of mind that it will be more able to resist abrasion, cuts and thorns when deflated. It will be interesting to see what pressure will provide the optimum footprint.

Dunlop will be introducing this tyre to the retail sector from March, through Dunlop Zone stores and selected 4×4 retailers. It is aimed squarely at the off-road fraternity, from farmers to overlanders, and through to commercial users such as mines, who need a tough, no-nonsense tyre. It will be available in 13 sizes with a variety of load and speed ratings (see sidebar). Of these, 10 are LT construction (in 15-, 16- and 17-inch), plus three sizes in PC (Passenger Car) construction in one each of 16-, 17- and 18-inch. This covers a very wide spectrum of needs, from SUVS to bakkies of every description, including heavier-duty 4x4s from Land Cruisers and Patrols to Defenders and Hummers.

According to Dunlop, the AT3G is a development of the original and successful Grandtrek AT1 which was OE spec on the Land Cruiser 70 Series (as a 265/70 R16). Made at the Sumitomo Rubber Industries factory in Thailand, the new pattern features a number of modifications aimed at making the tyres more rugged. These include wider grooves to assist grip and water evacuation, and a staggered pattern extended further into the shoulder, again to assist grip at lower pressures. So-called stone ejectors have been included in the shoulder grooves to aid self-cleaning and prevent stone drilling. Apart from the hardy three-ply sidewall internals, there’s also a thicker shoulder buttress derived from the rally tyres, to prevent damage by penetrations from rocks, roots and other road hazards.

Time will tell. We are going to head the Mazda’s tyres to the Karoo, the Eastern Cape and a few other demanding destinations in the next few weeks. We’ll drive them on tar, gravel and a few 4×4 trails to see how they measure up to daily use, and report back on grip, wear and overall experience.

THE SIZES