In mid-October Adventure Afrika embarked on the first all-terrain tyre test in over five years. Before the start of the test the venue, Klipbokkop in the Western Cape, experienced heavy rains and the influence it had on the results of the tyre test was tangible. The results from that test showed a completely different picture than what was anticipated.
But before we get to the result, what is an all-terrain (AT) tyre and are all created equal? According to Google an all-terrain tyre is a mix of highway tyres (HT) and mud-tyres (MT). That means AT tyres are great for daily driving, most weather conditions, and some dirt or mud – if you regularly navigate paved, gravel, and dirt roads, AT tyres might be the perfect choice. But all terrain tyres also have different applications and split between road and off-road, they can start off from 80/20 between road and off-road to a difference of 50/50. The difference between three ply tyres and two ply tyres also has an impact on the robustness of the tyre and its capability to prevent sidewall punctures.
We used the Klipbokkop 4×4 Academy near Worcester as testing venue. This was done for several reasons: the most important being its versatile terrain, with an excellent mixture of tar, gravel, sand and rocky routes – ideal for our purposes. The spectacular scenery was a bonus… Klipbokkop has been involved in tyre testing for nearly two decades, and the venue has been rated as a world-class off-road testing venue. So, the team, under the expert guidance of Gerhard Groenewald, know their way around tyres.
Since gravel, sand and rocky terrain are unstable by nature, the greatest dilemma of testing in this type of terrain is to ensure measurability and repeatability. No prescribed testing procedures exist for off-road tests in ‘real world’ conditions, and it took time and effort (as well as input from the manufacturers and organisations within the tyre industry) to devise measurable tests. The most important consideration was to find off-road orientated tests that simulate local conditions, and we finally completed six tests – two braking tests (one on tar, one on gravel), a gravel and rock traction test, a sand traction test, a sound test (measuring cabin noise) and a weight test.
We also wanted to do a wet braking test, but a deluge the day before we started testing made this impossible as the road we wanted to use was completely flooded. An acceleration test was also contemplated but rejected as we previously found that the results of this exercise were more down to the vehicle’s traction control system (it cannot be switched off completely) than tyre behaviour. A test measuring sidewall strength was also discarded, as it could not be standardised due to differences in tyre sidewall construction, leading to questionable results. We also contemplated a dirt handling test but rejected it since it was clear that even with continuous track maintenance, changing grip levels made any measurable result impossible.
To ensure maximum control, the following pre-event procedures were followed:
• To prevent the supply of any specially prepared tyres, most sets were procured through the Tiger Wheel & Tyre network.
• Where not possible (as some tyres were on special order), the sets were inspected by representatives of other tyre manufacturers as well as a technical committee.
• After fitting all the tyres, they were inflated to 3 bars and left to seat for about a day.
• All fitting was done by expert technicians from Tiger Wheel &Tyre on the same machine, and tyre changes were done in front of the different tyre company representatives.
For the tests, the following control measures were imposed:
• A control tyre (Goodyear Wrangler Adventure AT 17-inch) with a more on-road bias was specifically chosen to ensure no 18-inch tyre would gain an advantage.
• Control runs were regularly completed for the sand traction and incline traction tests to establish a reference point and repeated during testing to reconfirm this point.
• For the tar braking test, each set was driven beforehand, and a practice stop done to increase temperature. Tyre pressures were checked before each test run sequence.
• At least three runs per tyre were allowed. If a run was not representative (for instance when the speed was too low before braking), up to two extra runs were allowed.
• The best and worst runs were dropped and the average of three runs was recorded.
• The tracks for the traction and incline tests were regularly checked and maintained.
• The prescribed tyre pressures were confirmed on the test vehicles before every test.
• Representatives of all tyre manufacturers were invited to attend the tests. They could also appeal, should they pick up anything untoward.
• A technical committee consisting of a representative from Klipbokkop, as well as three different tyre brands, was elected daily to address any problems or complaints. The decision of this committee was final.
• Representatives from the controlling bodies in the tyre industry (SATMC and TIASA) were invited as independent observers.
Firstly, given the small points and percentage differences in our test results, it is clear that nowadays one will not find a low quality or bad AT tyre distributed through official channels. Also of interest is the influx of new imported tyres, and their ever-improving performance compared to established brands. It is also interesting to see how quickly tyre technology is evolving, with synthetic materials playing an even greater role in each new-generation tyre. This leads to greater competition amongst all the brands as they try to find an edge over their opponents, resulting in better, safer, and more efficient products.
In our tests the notion that a more aggressive tread pattern will fare better off-road did not necessarily ring true, as it confirmed a smoother tread could be advantageous, especially in sandy conditions. It also showed that tyre pressures are of utmost importance. Some tyres in our test – such as the BFs, Gripmax, Apollos and Radars, as well as the Dunlops and Coopers – may have performed better with lower pressures. That said, some manufacturers are finding better ways to build stronger and lighter AT tyres with high load and speed ratings, and sturdy sidewalls. It is therefore imperative that you make very sure for what purpose you are acquiring a specific tyre. We cannot stress this point enough.
Like with so many things when kitting out your overlander, choose the tyre that will serve your purposes best! If you need to regularly lug heavy loads over long distances, also off-road, rather choose a more robust tyre with a high load rating (120 R or S), but if you are going to use your vehicle mostly on-road, and only want to transport light loads, rather opt for a less rugged pattern.
With the 2023 AT TYRE TEST this all became very clear, as the conditions after the rains, the track and the different tests brought a completely different outcome in the scoring than what was expected. The track suited the more highway-orientated tyres, but not much. However, this trend followed right through with all our tests and the best preforming tyre was an unexpected surprise – the General Grabber AT3 normally outperforms all the tyres in these tests, yet it ended up somewhere in the middle.
Our results table became a sliding scale with a difference in overall performance of less than 8%. On the one side of the scale were all the highway-orientated AT’s (tyres with a highway to gravel orientation of 70/30 or more) and on the other side of the scale was the more off-road-orientated all-terrains (tyres with a highway to gravel orientation of 60/40 or less) This meant that we now had a good indication of what tyre was the best choice for a specific application.
The winner in this test was great for daily driving from work and back with the occasional venture into the bush or the dunes in Mozambique. If you picked a tyre around the middle 6th – 11th you were more likely driving to work and back each day but definitely spend a good amount of time on gravel or overlanding. Those in 12th position and higher are for people who spend most of their time in the vehicle off-roading. Also, please guard against generalising the results of this test – it was done under a specific set of circumstances, and therefore the outcome won’t necessarily hold true under different conditions. Rather see it as a guideline for your tyre application. And lastly, always keep in mind a specific tyre’s requirements and limitations before you hit the road – on or off the beaten track.
For the full article and results pop into your nearest SPAR, Pick n Pay or Checkers for a copy of issue 35 of Adventure Afrika/Avontuur Afrika