Quality off-road rubber is the easiest and most effective modification you can make to a new 4WD, so we’ve crunched the numbers on the Toyo Open Country range to take the guess work out of your upgrade.
When asked by the bush-wizards at Unsealed 4x4 if I’d like to lend a hand in putting five of the hottest mid-sized off-roaders through their paces, I first had to pinch myself before blurting out an affirmative response that gave them no time to change their mind.
Leaving my desk behind, we hit the open road for a week of tough testing across rivers, rocks, ruts and mud, all while nit-picking the features that would help or hinder the average motorist in everyday use.
Behind the wheel, all were packed to the brim with features that made them incredibly capable off-road but in one way or another, each was let down in the traction department, and I found myself daydreaming about how much better they’d be on Open Country rubber.
You see, advanced suspension designs, electronic assists and locking differentials are fantastic to have straight off the showroom floor but none of these can be used to their full potential if your tyres aren’t up to the terrain. For that reason, I’ve put together this fitment guide to give prospective buyers the down low on the first step towards off-road success; the right tyres.
The world of 4x4 modification is endless and we’re sure many will push these vehicles far beyond what the manufacturers intended but to keep things simple, I’ll provide suggestions on straight O.E. replacement, something slightly larger but within the 50mm diameter increase guidelines* and then something for those with dreams of going big (with an engineer’s approval of course).
Despite comparatively lacklustre sales figures, the Toyota Fortuner sat head-and-shoulders above the pack due to its exceptional build quality and design features targeted towards the off-road enthusiast, like the factory provisions for a second battery, removable rear seats for shelving and staunch under-body protection.
Typical of Toyota, the Fortuner featured the most refined electronic assists of the bunch but these proved to be of little use when we hit loose mud, where the Open Country M/T, or even the Open Country A/T II, would have allowed the A-TRC and rear diff lock to pull it through instead of getting bogged.
O.E. Replacement
- LT265/65R17 Open Country A/T II (Fortuner GX + GXL)
- LT265/65R17 Open Country M/T (Fortuner GX + GXL)
- 265/60R18 Open Country A/T II (Fortuner Crusade)
Legal Upgrade
- LT265/70R17 Open Country A/T II (31mm taller than 265/65R17)
- LT265/70R17 Open Country M/T (31mm taller than 265/65R17)
- 285/60R18 Open Country A/T II (24mm taller and 20mm wider than 265/60R18)
Engineered Upgrade
- LT285/70R17 Open Country A/T II (56mm taller and 20mm wider than 265/65R17)
- LT285/65R18 Open Country A/T II (52mm taller and 20mm wider than 265/60R18)
Presenting exceptional value for money, the Holden Trailblazer surprised us all with its gadget-packed leather interior and strong performance, earning the second spot largely because of its impressive off-road ability and class-leading 147kW/500Nm 2.8L engine.
As the only vehicle to feature a rear limited-slip diff, the Holden TrailBlazer walked through most obstacles with little thought required outside of a choice between high or low range and the selection of a good line, although its punchy powerplant could have made good use of extra traction on Toyos.
O.E. Replacement
- LT255/65R17 Open Country A/T II (Trailblazer LT)
- 265/60R18 Open Country A/T II (Trailblazer LTZ + Z71)
Legal Upgrade
- LT265/65R17 Open Country A/T II (12mm taller and 10mm wider than 255/65R17)
- LT265/65R17 Open Country M/T (12mm taller and 10mm wider than 255/65R17)
- LT265/70R17 Open Country A/T II (40mm taller and 10mm wider than 255/65R17)
- LT265/70R17 Open Country M/T (40mm taller and 10mm wider than 255/65R17)
- 285/60R18 Open Country A/T II (24mm taller and 20mm wider than 265/60R18)
Engineered Upgrade
- LT285/70R17 Open Country A/T II (68mm taller and 30mm wider than 255/65R17)
- LT285/65R18 Open Country A/T II (52mm taller and 20mm wider than 265/60R18)
Building on reliability in the commercial sector to push further into Australian households, Isuzu’s MU-X presents families with a trusty work horse hidden under the guise of a luxurious all-rounder that found itself in the middle of the pack.
A feature-filled leather interior complemented a grunty engine and gearbox combination to create a comfortable driving experience but we couldn’t overlook the fact that the Isuzu MU-X was the only vehicle with an open rear diff, something that additional traction from off-road tyres may have masked but that still felt like a glaring omission, especially without the assistance of traction control in low range.
O.E. Replacement
- LT245/70R16 Open Country A/T II (MU-X LS-M)
- LT255/65R17 Open Country A/T II (MU-X LS-U)
- 265/60R18 Open Country A/T II (common size to replace MU-X LS-T's 255/60R18)
Legal Upgrade
- LT245/75R16 Open Country A/T II (30mm taller than 245/70R16)
- LT245/75R16 Open Country M/T (30mm taller than 245/70R16)
- LT265/65R17 Open Country A/T II (12mm taller and 10mm wider than 255/65R17)
- LT265/65R17 Open Country M/T (12mm taller and 10mm wider than 255/65R17)
- LT265/70R17 Open Country A/T II (40mm taller and 10mm wider than 255/65R17)
- LT265/70R17 Open Country M/T (40mm taller and 10mm wider than 255/65R17)
- 285/60R18 Open Country A/T II (36mm taller and 30mm wider than 255/60R18)
Engineered Upgrade
- LT265/75R16 Open Country A/T II (54mm taller and 20mm wider than 245/70R16)
- LT265/75R16 Open Country M/T (54mm taller and 20mm wider than 245/70R16)
- LT285/70R17 Open Country A/T II (68mm taller and 30mm wider than 255/65R17)
- LT285/65R18 Open Country A/T II (64mm taller and 30mm wider than 255/60R18)
Packing a powerful 3.2L donk that’s proven popular in the Ranger and as the only full-time 4WD vehicle to be tested, expectations were high for the Ford Everest, although an overly-confusing interior that served as a constant reminder that you were driving the only base model at the $55,000 price point contributed at least partially to its fourth-place finish.
What absolutely cemented this position, however, was a poor gearbox tune that completely missed the meat of the engine’s 143kW/470Nm output. This was a real shame as when shifted manually, the Ford Everest performed quite well off-road, although the extra weight did make it the most likely to spin wheels, which could easily be fixed with some good rubber.
O.E. Replacement
- LT265/65R17 Open Country A/T II (Everest Ambiente)
- LT265/65R17 Open Country M/T (Everest Ambiente)
- 265/60R18 Open Country A/T II (Everest Trend)
- 265/50R20 Open Country A/T II (Everest Titanium)
Legal Upgrade
- LT265/70R17 Open Country A/T II (31mm taller than 265/65R17)
- LT265/70R17 Open Country M/T (31mm taller than 265/65R17)
- 285/60R18 Open Country A/T II (24mm taller and 20mm wider than 265/60R18)
Engineered Upgrade
- LT285/70R17 Open Country A/T II (56mm taller and 20mm wider than 265/65R17)
- LT285/65R18 Open Country A/T II (52mm taller and 20mm wider than 265/60R18)
Rounding out the field was the Mitsubishi Pajero Sport, a vehicle that outclassed the competition on sealed roads and offered flexibility with its ‘Super Select’ 4WD but was let down by long overhangs that amplified its lack of ground clearance off-road.
The 8-speed gearbox did a fantastic job of keeping the smaller 2.4L engine on song in both high and low range, so with stronger under-body protection, a lift and/or some taller tyres, the Mitsubishi Pajero Sport could be quite capable off-road and a damned comfortable daily driver to boot!
O.E. Replacement
- 265/60R18 Open Country A/T II (Pajero Sport GLX + GLS + EXCEED)
Legal Upgrade
- 285/60R18 Open Country A/T II (24mm taller and 20mm wider than 265/60R18)
Engineered Upgrade
- LT285/65R18 Open Country A/T II (52mm taller and 20mm wider than 265/60R18)
*When selecting new tyres or rims, it is always best to check with your local regulatory body but the Department of Infrastructure’s National Code of Practice (Section LS 4.2) does provide general guidance for tyre sizing, stating that aftermarket tyre sizes fitted to 4WD or AWD vehicles “must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle.” This was used to calculate suggestions based on the tyre sizes fitted to models tested as these were the tallest available for each vehicle but recommendations have also been made on tyres fitted to other trim levels where possible.
