Terrain Response


Words by Grant Spolander. Pictures by Andrew Middleton and Grant Spolander.

If you’re in the market for a new set of tyres, you may find yourself torn between buying all-terrains (ATs) or mud-terrains (MTs). The easy way to decide is to base your decision on the industry trend, where ATs significantly outsell MTs. However, when you consider that an average set of tyres can last five years or more, and set you back R15k, it’s an investment you want to be sure of. From an environmental perspective, it’s believed that ATs are less damaging to the terrain than MTs; so, if you’re that way inclined, the decision is simple. But… one could argue that an MT tyre offers greater traction, and, therefore, is less likely to spin and cause serious damage to the environment.

For the last year or so, we’ve been testing two sets of tyres: Cooper’s AT3s, and STTs. The former is an advanced new generation all-terrain, and the latter, an aggressively-designed mud-terrain. We tested both tyres on tar, gravel, rock, sand and mud. The results of this test were fairly conclusive; but, somehow, it doesn’t make the AT-versus-MT decision any easier. Cooper describes their AT3 tyre as having a 70% bias towards on-road use, and the remaining 30% dedicated to off-road performance. In contrast, the STT features an 80 / 20 split, erring on the side of being a full-blown offroad tyre. You may find it hard to gauge what these figures actually mean. For example, do these percentages relate specifically to these tyres, or do they mean that the STT is 50% better, off-road, than the AT3?

In a subsequent write-up (see our April ‘14 issue), we raised the subject of footprint versus tyre pressure. We said that no two tyres are alike; and that what one tyre does at 1.0 bar may be completely different to how another performs at the same pressure. We used the AT3 and STT to highlight this fact, and found that the 3-ply-rated STT required (on average) an extra 0.2 bars of deflation in order to match the footprint of 2-ply-rated AT3. In other words, it wouldn’t be fair to say that one tyre performs better in sand than another, when both tyres have been tested according to pressure, and not footprint.

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