Everyone packs for the trip and nobody checks the tyres. The cooler box gets more attention in October than the five things actually holding the vehicle off the road.
If you are heading onto dirt this summer, whether that is the road into a game farm, the Karoo back roads or a week in the Kalahari, it is worth knowing that gravel does not break tyres the way tar does. The failure mode is different, and so is the preparation.
Gravel attacks the side of the tyre
On tar, tyres wear out. On gravel, tyres get cut.
A graded dirt road is covered in stones with freshly broken edges. As the tyre rolls and flexes, those edges work against the sidewall, which is the thinnest and most flexible part of the whole casing. The tread is thick, reinforced with steel belts and designed to be chewed on. The sidewall is not.
That matters because of one hard rule: a cut sidewall is not repairable. A nail in the tread is often a repair. A stone cut through the side is a new tyre, generally right there and then, usually a long way from anywhere that sells tyres.
Corrugation adds the second problem. Sustained speed over washboard surfaces puts repeated flexing and heat into the casing, and heat is what causes structural failures.
Which tyres are best for gravel roads?
Tyres with reinforced sidewall construction and a tread pattern that clears loose material, which in practice means an all-terrain tyre rather than a highway one. The key specification is not the tread pattern most people shop for, it is how tough the casing is, and whether its load index suits a fully packed vehicle.
Three broad categories, and what each trades away:
Highway-terrain. Quiet, comfortable, efficient on tar, and the most vulnerable to stone cuts. Fine for a graded district road in good condition. Less fine for sharp, rocky tracks.
All-terrain. Chunkier tread blocks that bite into loose surfaces, and usually a tougher sidewall. Slightly noisier on tar and slightly thirstier. The sensible middle for a vehicle that does both.
Mud-terrain. Aggressive open tread for deep mud and sand, with the toughest casings. Loud on tar, and they sacrifice a lot of on-road manners for terrain you may never actually drive.
Most people over-buy here. A bakkie that spends fifty weeks a year on tar and two on dirt does not need a mud-terrain tyre, and will be living with the noise for the other fifty.
What are the best all-terrain 4x4 tyres in South Africa?
We do not rank tyre brands, and anyone who gives you a definitive list is usually selling one of them. What we can tell you is what to compare on the sidewall: the load index against the weight of your loaded vehicle, the construction rating, and whether the tyre is built with reinforced sidewalls rather than just an aggressive-looking tread pattern.
That load index point is worth dwelling on. A vehicle packed for a week away, with water, fuel, a fridge, recovery gear and people, weighs a great deal more than the same vehicle doing the school run. The index is the coded number after the size on the sidewall, and it maps to a maximum weight per tyre in tables the manufacturers publish. We explain where it sits in the marking in how to read your tyre sidewall.
Buy for the loaded weight and the worst surface on the itinerary, not the average one.
Should you lower tyre pressure on gravel roads?
Many experienced dirt-road drivers do, because a slightly softer tyre absorbs impacts instead of transmitting them and puts more rubber in contact with a loose surface. Follow the guidance from your vehicle and tyre manufacturer rather than a figure off a forum, keep your speed down to match, and reinflate before you get back onto tar.
The forgetting is the dangerous part. A tyre deflated for gravel and then driven at highway speed on tar is running well under its correct pressure, building heat in the sidewall exactly where the cuts and flex damage already are. If you let air out at the farm gate, put it back at the filling station.
Our full cold-checking routine, and why the placard figure matters more than the number on the tyre, is in tyre pressure: the two-minute check.
What should you inspect before a long gravel trip?
All five sidewalls for cuts and bulges, the spare’s age and pressure, the jack and brace, a gauge and a way to inflate, and pressures set cold for the loaded vehicle. Do it a week before you leave rather than the morning you go, so there is time to act on whatever it turns up.
Working through it properly takes about twenty minutes.
- Sidewalls on all five tyres. Cuts, scuffs, bulges and fine crazing. A bulge means the structure has failed and that tyre is finished.
- The spare, properly. Pressure, date code, and whether the carrier bolts still undo. On a dirt trip the spare stops being theoretical. The method is in the spare tyre problem.
- Jack and brace. That they are present, that they fit, and that the jack works on an uneven surface, which is not the same as working on your driveway.
- A pressure gauge and a way to inflate. A compressor matters far more on dirt than on tar.
- Pressures set cold against the loaded figures on your placard.
On remote routes, a second usable spare is worth the space. A sidewall cut cannot be plugged at the roadside, and two failures in one day on a track with no signal is the situation that ruins a trip.
What we can honestly do for a gravel trip
Our Nano Polymer coating goes on the inside of the tread and cures there. In the tread, it seals as it happens, and in most cases you can keep rolling to somewhere safe. On a bushveld track that covers thorns, and on a district road it covers the screws, wire and stones that work into the tread.
Now the part that matters more on gravel than anywhere else. The coating does nothing for a sidewall cut. Nothing for the bead, nothing for impact damage that breaks the casing, and nothing for damage already in a tyre. Since the sidewall is how gravel usually finishes a tyre, we would far rather you went in knowing that than found out in the Kalahari. Exclusions are printed above the coverage on the 1.6 Guarantee page for exactly this reason.
Protected tread and a good spare is a sensible combination for dirt. Protected tread alone is not a plan.
Before the December trip
If you are going onto dirt this summer, book the fitment while there is still time to act on whatever the inspection turns up. Send a photo of the tread and both sidewalls to +27 76 089 4066 and tell us where you are going, and we will tell you what we would treat and what we would replace first. The booking page has the calendar.