Tyres

Tyre FAQ: 90 Series Prado

Needing to replace those balding Grand Pukes, or just looking for a more suitable tyre for the work you do with your truck? I’m attempting to decipher this can of worms. There are lots of opinions about tyres and lots of them conflict but here goes.

General considerations:

GXL,TX,VX models come standard with the 16x7 inch rims and 265/70R16. Steel on the GXLs.
RV models come with 16x6 inch rims and 215/80R16.
The standard Dunlop Grandtreks had a chequered history when they came out on the 80 series (many punctures) but the 265/70 fitted to the Prado are better tyres. They usually give 60-100,000km but when used offroad occasionally get a sidewall bulge to tell you that a cord's busted and the tyre is dead. These tyres are light, quiet and give good fuel consumption. They are a bit underrated.
Many Prado owners who go offroad will upsize to the LT265/75 tyres. Those who don’t offroad usually stick to P265/70. Hard core people upsize to LT285/75R16.
Benefits of 265/75 are greater diameter (+30mm)(longer footprint, better floatation), greater ground clearance (+15mm), stronger LT construction and higher load index (usually 119 to 122 instead of 112), and they are actually cheaper.
Consider the legalities of taller or wider tyres and check with your local authorities and insurance company.
Fitting 265/75 or 235/85 tyres will change your speedo by 3% on a GXL,VX,TX or by 6% on an RV.
Larger tyres, and more aggressive tyres will increase fuel consumption by as much as 10%. They weigh more and may have increased rolling resistance.
Taller tyres should be accompanied by a suspension lift to avoid the slight rubbing that can happen with some (square shouldered) brands. Common place to rub is on the bulge of the front mudflaps.
Chunky, fat tyres use more fuel than the Grand Treks which have a low rolling resistance.
RV models with 7 or 8 inch rims will require flares.
There are no advantages to using 8 inch (80 series or Patrol) rims on a Prado. Tubeless 265 tyres are easier to inflate on 7 inch rims than 8 inch rims.
15 inch rims don’t fit Prados as they touch the rear calipers.
Tyre noise is rarely a problem on Prados (good sound insulation). BFG Muddies give a pleasant hum only.
Prados are a lighter vehicle than Patrols and other Land Cruisers – tyres are not stressed as much and can be run at lower pressures than our friends with the heavier vehicles.
Most RV owners with 215/80 Grandtreks on 6 inch rims replace them early because of poor handling and rapid shoulder wear.
Mud-Terrain tyres only come in 225/75, 245/75 and 265/75 sizes for Prados. 255/85 and 285/75 are pretty tall (840mm dia) and require some work with the grinder and FB hammer at the front to get adequate clearance.
Split rims are available on all other Land Cruisers. They were once popular because it was sometimes easier to fix punctures. I had many years experience with splits but would never go back to them because tubes fatigue, seams splitting, and the tyres wear out quicker because of heat build up. Split rims are also about 6 kgs heavier. If you’re desperate for splits, you can fit the 80 series splits. The 60 series splits have about 55mm less backspacing which exposes the brakes, may make the steering a bit heavier and may lead to front tyres touching the front mudflaps.
Chunky fat tyres that fill up the wheel wells look the part!

Tyre Size:

Standard fitment:

RV models: 215/80R16 Dunlop Grandtrek TG20 fitted to 16x6 rims with 118mm backspacing. These have a 107S load rating (975kgs per tyre). Diameter 750mm.

GXL,TX,VX: 265/70R16 Dunlop Grandtreks TG35M2, fitted to 16x7 rims with 118 mm backspacing. These have a higher 112S load rating (1120kgs per tyre). Diameter 778mm.

Alternative sizes:

* Upsizing should be accompanied by a suspension lift.

16x6 rims:

225/75R16 (dia. 742mm). Must have a load rating of at least 107. So BFGATKO are OK (LR 110) but Grandtrek AT2 are not (LR 103Q).
235/70R16: forget them as the load ratings are usually too low.
235/85R16 (810mm dia) (I’ll leave you to decide the legalities). They fit the rims well, but may scrape the upper inside rear wells if mounted on the 6 inch rims and standard suspension is retained. I’d prefer to fit the 7 inch rims when fitting 235/85R16 tyres.

16x7 rims:

LT245/75R16 (dia 778mm) – come in heavier LT construction and have the same diameter as the 265/70 for those who want to keep the original diameter, gearing and speedo accuracy.
LT235/85R16 (dia 810mm) – Skinnier tyres are popular with desert travellers and these will also fit up to the 7 inch rims nicely.
LT265/75R16 (dia 810mm) – Popular choice because they fill up the wheel wells nicely.
P275/70R16 (dia 790mm) – Usually don’t come in LT construction except for BFG. They are slightly taller but still legal re diameter.
LT285/75R16 (dia 840mm) – touch everywhere – need an angle grinder to fit, and then have to consider the legalities, insurance etc. 255/85 are probably the same.

Flares:

Required for all models with 16x7 rims. For RV upgrades, the factory RV flares are probably the most popular because of price (~$350) and quality considerations. They come in black (looks fine) but can be sprayed. Rubber 35mm flares (~$125) are the cheaper and durable alternative.

Brands:

Here's where we open up the can of worms!!!

I think its fair to say that anyone who sticks to the bitumen will be happy with ANY choice of tyres on a Prado. Offroad may be a bit different.

BFGoodrich have earned a great reputation with offroaders over many years because of the great mileage and puncture resistance of the AT tyres. They were replaced by the ATKO’s about 2000, and some owners have been disappointed with the apparently softer rubber compound which can chunk out on sharp rocky outback roads. This is probably exacerbated by excessive loads, tyre pressures and speed. Doesn't seem to happen as much on the Prados (less weight). Still get very few punctures, are quiet and many owners still get good mileage. The Mud Terrains are popular with serious offroaders in the eastern states. Despite popular opinion, they are a very good sand tyre, and probably better than the ATKO in this respect.
Dunlops: actually have a pretty good range of tyres. I know a lot of Prado owners who DO go offroad and who have had greater than 70,000 trouble free kms out of the 265/70 Grandtreks. I’ve heard good about their AT2 and MT2 in the 265/75 size although the load ratings of these tyres (112) is less than other LT tyres.
Bridgestones. The 604V was an excellent tyre in the 750R16 and 205R16 sizes and gave great mileage in the 10R15. They replaced this with the D693 a couple of years ago and the first batch of these were prone to punctures. Bridgestone Australia altered the construction and came out with a much stronger casing that they claimed was more puncture resistant than BFG. The Bridgestone 661 is a very strong tyre in the 235/85 size.
Coopers: Have entered the Aussie market with some good marketing. Like every brand you hear good and bad reports, but their Suretrac S/T is popular. The 265/75 looks nice on the Prado – bit more aggressive than many A/T tyres. But the siping is very close and the outer edges of these tyres easily chip out on rocky terrain. They are pricey. Their “80,000km” warranty is pro-rata and has too many conditions on it, so leave that out of the equation.
Kellys have a good reputation in South Australia for being a strong tyre at a good price. Not sure about elsewhere.
Goodyear MTR: Fast becoming one of the most popular of the aggressive offroad tyres because they have a strong tread (don't easily chip), three ply construction to resist punctures ('a la BFG) and look nice and aggressive. Not very noisy either. Pricey as well.
Hankooks, Kumho, Yokohama, Toyo, Pirelli, Firestone, GT Radial, etc etc – I can’t comment from experience.

Tyre Pressures:

Another can of worms.

Bitumen:

Factory recommendations for the GrandTreks are Front 26psi and Rear 26/29. These pressures give a good ride, but the fronts may wear out on the edges. Most owners run a few psi higher than this on bitumen. Tyres with the higher load ratings need higher pressures on the bitumen. My Mud-terrains need 38/40psi on bitumen.

Dirt Roads:

Opinions vary from “never below 40psi off road” to “never above 24 offroad”. The high pressure lovers usually have done so for many years and often are referring to their split rims, which don’t like the lower pressures.

With the tubeless rims and tyres on the Prado, lower pressures as soon as you’re off the bitumen seems to make sense. Adam Plate’ from Oodnadatta roadhouse advises to use no more than 25 psi on outback dirt roads. This pressure allows for some “give” in the tyre and prevents sharp rocks from penetrating the tread. (Tried puncturing a balloon at low pressure?). Seems to hold true on a lot of our club trips in recent years. Corrugations are better at lower pressures, and shocks don’t seem to suffer as much.

Sand:

Soft sand can be handled at very low pressures. (20>16>12>8 psi) Just make sure you don’t turn sharply because this tends to roll the bead off tubeless rims. This is a minor problem as most of the time, a 265 tyre on the 7 inch rim can be reinflated with a good pump.

Desert trips – 18/20psi does me fine – makes life easier for your suspension as well.

Punctures:

These are best avoided. Lower pressures, don’t overload, never drive faster than 80 kph on the outback roads, use tyres that have greater than 50% tread, LT tyres with higher load ratings.

Puncture Repairs:

No sweat methods: Always take a tubeless plug repair kit and know how to use it. Every kit seems to use a different method. Most punctures are easily fixed with one or several plugs often without having to take the wheel off. Get the tyre repaired properly at the next town because casing damage may be more extensive than it appears from the outside. In the bush, partial sidewall splits can be temporally repaired using Loctite 406 superglue, but a split in the sidewall will often spell the death of the tyre so get it checked when back in town.

Sweat method: Beadbreaker, levers and hammer. Leave it to the experts if possible. I’ve got better things to do when I go bush! Always carry a spare tube in case a tyre can’t be reinflated tubeless or you need to salvage one for a spare if desperate. See the LCOOL tech pages for a no sweat beadbreaker using the vehicle’s jack – actually best for alloys.

Rims:

6x16 inch rims are mostly steel, although the “Getaway” and “World Cup” models in Oz came with 6 inch alloys.

7x16 inch rims are steel on GXL (very good strong rim) while there were at least 3 types of factory alloys. Early VX had 5 spoke Kimberley alloys; Later VX/TX had three spoke alloy while the last of the GXLs had 6 spoke Kimberley alloy. All alloys require different wheel nuts – the VX/TX require 21mm nuts with a long shaft, while the 6spoke Kimberley require 19mm nuts and an adaptor for the brace. Also have to remove the steel washer off the spare tyre locknut.

ROH make 16x7 and 16x8 rims with about 104mm backspacing. These rims increase the track slightly so fit up to the Prado very well. Plenty of aftermarket alloys around as well. Prados have the same thread wheel nuts as all other Land Cruisers prior to the 100 and 78 series.

Wheel studs: Have been known to break! Avoid this by lubricating the threads of all studs with a dab of grease or antisieze. Tighten nuts to 113Nm only. I carry spare studs – the front and rear studs are different, so carry a couple of each.

My Preference:

For most offroading: My personal preferences are to use a 265/75R16 on a 7 inch rim, with a load rating of about 119 (8 ply equivalent). I run two sets of 4 rims – one set of MTRs and one set of Kelly ATs. I carry one spare casing and tube on most trips.

Phil G

21/1/2004

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