Big Tyres: Pros and cons

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Originally Posted by PhilipA

IMHO it is a bit of a zero sum game.
So you're on this track and see a nice mud puddle up ahead, so you gun through it. Feel top of the world.
Then someone comes along with tyres 1 inch bigger than yours and guns through. So you come along and guess what? You get stuck in the middle of the bog!
So then you HAVE TO get larger tyres so that you can again gun through the bog, ignoring the fact there is a bypass road around the bog.
AND SO ON.

Larger diameter tyres have a better angle of attack on rock steps and can be aired down more without losing ground clearance, BUT unless this is all you do with your car there are lots of downsides.

Your gearing on the highway is now way out, so no problem fit low ratio diffs.
You now are breaking axles regularly. No problem fit HD axles.
You now break CV joints regularly. No problem etc.
In the search for ever larger tyres , you now need a 4 inch lift and body lift. No problem just spend some more money.
You now have big tyres on at low pressures and you bend all your steering rods and break the tie rod ends. No problem etc . the power steering can no longer cope so you fit a full hydraulic ram steering. No problem etc.

You now have a $10K car that you have "invested" $50K into and it is still worth $10K or less and drives like a pig on anything but gnarly trails.
Regards Philip A

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100% agree

I've just purchased a set of 235/85/16 KM2's on a nice set of wheels and have no issues with the modifications required to fit them to the RRC. I hardly call that a 'big tyre' mod, but it still requires a decent amount of work to make them fit.

I have had 225/75, 245/75 and now 265/70 tyres on my Disco, with no noticeable difference in fuel consumption, but with vast differences in handling and off-road ability. The best tyre was the 245/75R16.


Adding a 2 inch lift to the V8 made no difference in fuel consumption, no surprise there.


Years ago I saw my first Cruiser with massive tyres, on an Outback road. The darn thing looked skittish and couldn't cut into the road below the loose surface. Have no idea what it's tyre pressures were, so lets forget that part of the equation. But, my overladen D1 V8 with 225/75 tyres was great to drive.


Noting that larger tyres in some form make off-road work easier, what have people found to be a good compromise on their vehicles? e.g 265/75R16? What is too big?


Disco 1?
Disco 2?
110/Defender (tin can with wheels)

Just to re-ignite this debate :)
Two days in a row I've managed to get my in-laws toyota bogged in thick, gloopy mud doing work around the property.
Guess what?
It runs skinny tyres ;)
Tall, skinny mud tyres.
I did manage to extract it today with much backwards and forwards and associated hooha, but yesterday it required a snatch out.
From my D2, with tyres that are more biased towards the wide side of things.
Drove on the same ground, didn't get stuck.
Why?
Because it DIDN'T break the surface, merely floated over the top :cool:
Skinny tyres might be great when there's actually hard ground under the slop, but I could have spun these tyres until I was in China.
Now, I need to go see a tyre man about some 265/75s :D

Quote:

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Originally Posted by Disco Muppet

Just to re-ignite this debate :)
Two days in a row I've managed to get my in-laws toyota bogged in thick, gloopy mud doing work around the property.
Guess what?
It runs skinny tyres ;)
Tall, skinny mud tyres.
I did manage to extract it today with much backwards and forwards and associated hooha, but yesterday it required a snatch out.
From my D2, with tyres that are more biased towards the wide side of things.
Drove on the same ground, didn't get stuck.
Why?
Because it DIDN'T break the surface, merely floated over the top :cool:
Skinny tyres might be great when there's actually hard ground under the slop, but I could have spun these tyres until I was in China.
Now, I need to go see a tyre man about some 265/75s :D

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Very few people have experience driving on (in) proper mud ;) that's what you just observed Mr Muppet :D

He is also comparing a Land Rover to a Toyota. So not a fair comparison by any means! ;)

The old tojo ain't that bad. Goes where its pointed most of the time.


Sent from my HTC One using AULRO mobile app

Many years ago I worked in qld govt as a hydrographer and our vehicle was the venerable 75 series ute with a huge custom rear, load modified for about 3.6t.

It ran standard split rims and a/t's. used to go through lots of boggy mud, as you do when flood gauging etc. There was no way you would complete a week long field trip without getting the winch out at least once.

There is definitely an art to driving the standard tyres in waterlogged silt and clay.

land anchors and pto winches aside, that 75 and it's 1HZ diesel got us through some pretty hairy moments. As much as I understand this arguments merits and foundation, I have to say it simply is not what I have personally experienced.
We had an 80 series for water quality sampling work and other less serious stuff, and it also used to come as a secondary vehicle on some of the flood trips. It had much wider 265 tyres fitted, and would get bogged quicker than you could sneeze. It got to the point where all the staff would run for the keys to the 75's if we were going on a flood trip. So it wasn't just me, it was half a dozen other guys who felt the same. the 80 was much better on dry dirt roads than the loaded 75 though.

Bear in mind, these were govt work vehicles, used every day, long trips, high mileage between destinations and often a lot of serious bashing to get to the gauging sites. No easy tracks or bitumen driveways here.
They would be fitted and spec'd up by the local toyota dealer (after purchase) to the specific govt requirements for the work, which included additional standards compliance and DOT modification plates. These were not standard spec vehicles. diff locks, heavy duty suspension, PTO's, racks, extra large sub tanks etc... there was a lot of serious stuff under those tojos. They were expensive, and suffered a hard but short (80,000km) working life before the custom bits & pieces would be transferred to a new chassis.

Still, I bought an RRC. because fundamentally there is one thing that separates them from each other.

Comfort.

And I'd rather be comfortably sitting in mud to the sills, surrounded by elegant appointments, than slumped in an ill-supporting toyota seat with a plasticky rubbery utilitarian interior.

Standard tyres on an RRC are pretty skinny too. I haven't been bogged in mine yet, and it's skinny half-worn 225/75 cooper at's have been places that have frightened big 265 MT shod landcruiser owners... Of course when they seee a guy in a standard RRC fjording a flooded creek, or descending a slippery muddy rocky fire trail, they just HAVE to follow... to prove a point (or something like that) and when they get bogged, stall or slide off a track, I have a quiet chuckle. There is nothing more amusing than having to snatch a landcruiser. I have all the good quips lined up for when they start making excuses.

I think I'll try and sum it up this way... While skinny tyres might be the argument, the vehicle theyre fitted to and the driving style have more to do with the equation than just the tyres themselves.

fwiw, Gwagens run some pretty skinny tyres. I've never ever been bogged in one of those. Had a mate who fitted some skinny 35" simex centipedes to his 300GD and that made the thing even more capable. Truthfully, it was unstoppable, and that is a heavy vehicle - about 3.3tonnes (empty) so perhaps it is more about the vehicles dynamics, than just tyres, or the driver.

I love the look of balloons under the wheel arches, but I'm not convinced there is any real positive that outweighs the negative. We shall see. I have some 235/85 KM2's here to shove under the RRC before xmas. Need to do a few mods to get them under though.

I think the disco, is probably a fair bit lighter and more agile than the landcruiser. One of the first things I noticed about the RRC when I got it was how much more articulation there is in a standard vehicle, than in a landcruiser. That may also go some way into explaining why the landrover products are superior offroad vehicles, regardless of tyre width.

Yeah, I'm skeptical about the wide tyres argument. I suspect it has more to do with appearance than practicality. And its fanned by the push by manufacturers to sell more products.

Last time I went to buy bigger tyres, the dealer said they wouldn't fit larger than standard. It's all coming down to getting sued for fitting 'incorrect size tyres' in the case of an accident! Regulating us for air soon!