Overland Tires: How to Choose, Inflate and How Many to Carry

Overland tires: how to choose, inflate and how many to carry

The tire is the preparation item that generates the most doubt and the most mistakes. Most Brazilian overlanders underestimate it because the car runs well in the city with the stock tire, and they discover on the first gravel road in Argentina or Bolivia that the problem wasn't the tire, it was the wrong type of tire for the wrong type of terrain. On ripio, the wrong tire isn't just discomfort: it's a guaranteed puncture, it's early wear, and on some stretches it's a real risk of an accident.

This article is the practical tire guide for overland travel. It covers what each type delivers, how to inflate for different terrains, how many spares to carry, and what to do when you get a flat far from any tire shop.

In short: for overland travel through South America, the all-terrain (AT) is the tire that best hits the balance between asphalt, ripio and light off-road. The stock highway (HT) can't take serious ripio. The mud-terrain (MT) is excessive for most routes. Carry two spares for any trip with a gravel stretch. Pressure varies: 32-36 psi on asphalt, 26-28 psi on ripio, 18-22 psi on heavy off-road.

The three types of tire and what each one handles

Highway Terrain (HT)

The tire that comes standard on most SUVs and pickups sold in Brazil. Excellent performance on asphalt, quiet, comfortable, fuel-efficient. On light ripio it holds up, but the compound is softer and the tread less aggressive. On severe ripio, the risk of a puncture rises and wear accelerates a lot. On a trail or in mud, it isn't the tire.

If the trip is 90% asphalt with one or two days of easy gravel, the stock HT passes. For anything more serious, change it before departing.

All-Terrain (AT)

The tire of most overlanders. A more resistant compound, an intermediate tread, it serves well on asphalt (more noise than HT, slightly higher consumption) and does very well on ripio, gravel, packed dirt and moderate off-road. In deep mud it starts to lose efficiency, but for 95% of South America's routes it's the right tire.

Mud-Terrain (MT)

A much more aggressive tread, a hard compound, made for mud and severe off-road. On dry asphalt it's noisy, less efficient and wears faster. On a heavy trail or in mud it's the best. For a conventional overland route through South America, ripio, desert, steppe, some wet stretches, it's excessive in most cases. If the trip involves many days of difficult trail, such as Amazon or Pantanal roads, then it starts to make sense.

Tire pressure, the adjustment most people ignore

Correct pressure makes more difference than the tire type on many terrains. The same rubber behaves completely differently at 36 psi and at 24 psi.

On asphalt: the manufacturer's standard pressure, usually 32 to 36 psi. Don't save by inflating less, irregular wear, excessive heating and higher consumption.

On ripio/gravel: reduce to 26 to 28 psi. The tire gains more contact area, absorbs the irregularities better and punctures less. The top speed drops, which is natural, on ripio you shouldn't exceed 80 km/h anyway.

On heavy off-road (rock, sand, mud): reduce to 18 to 22 psi. A larger footprint, better traction, lower risk of a puncture on sharp rocks. With such low pressure, avoid fast turns and high speed.

Important: when returning to asphalt, inflate back. Running on asphalt with a flat tire overheats the tire excessively and can cause damage or a blowout. Keep a reliable gauge and a 12V compressor in the vehicle, a cheap investment, enormous value.

How many spares to carry

A trip with 100% asphalt: one spare is enough.

A trip with many ripio stretches: two spares is worth considering, (if you're traveling alone). A double puncture on severe ripio isn't a rarity, a sharp rock catches two tires on the same pass. Whoever carries only one spare and punctures twice is left on foot, and then it can get complicated.

A long trip or one with very remote stretches: two full-size spares + a temporary repair kit (rubber plugs) for simple punctures that let you run to the tire shop.

Where to store it: the second spare, if the vehicle doesn't have a rear mount, goes inside the trunk or fixed to the roof rack. The investment in a rear spare-tire mount is worth it to free up interior space.

Tire repair kit, what to always have in the car

The basic kit fits in a small box and solves most simple punctures on the road:

Repair plugs (mushroom or spiral type): a temporary repair that lets you run to a tire shop. Easy to apply, works on 90% of tread punctures. Rubber cement: comes with some kits. Reamer and insertion tool: instruments to apply the plug. 12V compressor: mandatory. Without it, even with the repair done, you can't inflate the tire. Choose a model with a hose long enough to reach all the tires without moving the car. A jack suitable for the load: the stock jack of many SUVs and pickups can't take the load with travel gear. Check the capacity before leaving. The correct wheel wrench: it seems obvious, but check that the stock wrench unlocks your bolts, because bolts torqued at the factory sometimes don't give without an extension bar.

Wear and when to change before the trip

A tire with less than 4 mm of tread depth doesn't go on a long trip with ripio. The wear indicator is embedded in the groove, when the rubber reaches the level of the arrow, it's at the legal limit and at the real safety limit.

Old tires with still-good tread but more than 6 years since manufacture (date printed on the sidewall, WWYY format, week and year) start to harden and crack internally. In the high temperature of asphalt + heavy travel load, the risk of a blowout increases. Change before departing.

Before any long trip with ripio: rotate the tires (including the spare if it's full-size) and check the balancing and alignment. An unbalanced tire on ripio vibrates much more than on asphalt, and the vibration transmitted to the vehicle accelerates suspension wear.

Use GT Overlander to plan your route before deciding on the tire, with the path drawn and the ripio stretches identified, you decide with much more precision whether you need to switch to AT before leaving or whether the stock HT handles what the route demands.

FAQ

Is it worth switching to AT before a trip through Argentina?

It depends on the itinerary. Argentine Patagonia with the Carretera Austral or Ruta 40 with ripio stretches: very much worth it. Buenos Aires + Mendoza + vineyards on almost all asphalt: the stock HT passes fine. Map the ripio stretches of the itinerary before deciding.

Can I inflate the front and rear axles differently?

The manufacturer usually recommends different pressures for front and rear (the rear is usually a little fuller, especially with a load). Follow the table on your vehicle's driver door. It specifies by load.

Does an AT tire increase consumption a lot?

On average 5% to 10% more than HT on asphalt, depending on the brand and the profile. Consider this in the fuel budget for a long trip.

Is there a tire shop on the Carretera Austral or the Salar de Uyuni?

On the Carretera, in the bigger villages (Coyhaique, Cochrane) yes. On remote stretches between villages, no. On the Salar de Uyuni circuit, in Uyuni there is. On the stretch of the Bolivian lagoons (Laguna Colorada, Verde), there's absolutely nothing. It's where you most need two spares.

Can I use the "step-down" spare (smaller than the others) on ripio?

Technically you can get out of a jam, but a smaller mixed-use spare tire can't take ripio for many kilometers. The differential and the suspension pay the price. Drive slowly and change it as soon as possible for a correct-size tire.

To wrap up

The right tire is silent safety, you don't think about it while it's working. The wrong tire becomes the protagonist of the story at a time when you definitely don't want a protagonist. Switching to AT before a trip with serious ripio isn't an expense: it's the preparation item with the best cost-benefit on the entire list. And two spares in the trunk cost much less than a tow in the middle of the Bolivian Altiplano.