What factors make Off Road Ability?

Wider tires are worse in mud anyway. And those older forys are really light compare to those old classic toyos.
Subaru strong side is center of gravity and weight distribution and older toyos makes things even worse to make furniture and fridges in trunk.

Tire pressure and ground pressure are very different things though both are measured in psi.

As usual, I agree with [MENTION=15721]scalman[/MENTION],

Old 4x4s are obsolete. Btw, it is amazing that the prevailing 4x4 guides in 2018 are still written for vehicles from ca. 1990. They ignore not only modern AWD systems, but also modern Toyotas and Land Rovers. Habits are hard to change.

MiddleAgeSubie said:

Tire pressure and ground pressure are very different things though both are measured in psi.

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yah what?

tyre pressure and static 'ground pressure' are exactly the same number.

Even in a dynamic situation, they're very closely related - the main modulator is probably tyre carcass and tread stiffness.

What makes the Subarus so performant is the lightweight, the low center of gravity with the engine in front overhang helping weight distribution on uphill sections (better front grip than any other 4x4), soft springs and voilà !

You saying that we have soft suspension stock compare to others? I wouldnt call my car soft at all so maybe my shocks ate shot allready.
Then again too soft and you will have boat on high speeds too hard and its feels like wood car haha. I would call my car now half wood.

duncanm said:

yah what?

tyre pressure and static 'ground pressure' are exactly the same number.

Even in a dynamic situation, they're very closely related - the main modulator is probably tyre carcass and tread stiffness.

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Apparently not. There are ground pressure tables for CAT equipment that I noticed someone referencing and citing from. PSI is important but the two numbers are not the same. A bigger tire and a smaller tire of the same model on the same vehicle will have different ground pressure. Add airing down and the differences are dramatic.

You can read about that in a 4x4 book though a quick search found some info here, divide vehicle weight by contact patch: https://physics.stackexchange.com/questions/119786/does-the-pressure-inside-a-tire-equal-to-its-average-ground-pressure

Does not mean those are correct, of course, gotta find a scientific paper for that.

And if you were right about tire PSI being the same as ground pressure, then why does weight even matter? It would be all the same, right?

What matters here is that the point of how lightweight Subarus are is grossly overstated on this forum because it is based on comparing 1990s Subarus to 1990s Land Cruisers and Land Rovers.

Subarus tend to have miniscule tire contact patches, especially when equipped with LT tires for which the Subarus are too light, and the fact that they get by in spite of this shortcoming is what is most remarkable in some environments. While it is true that narrow tires can be beneficial in some scenarios (like snow or shallow mud over generally sound ground), you want wide tires for flotation over sand and deep mud as well as challenging rock environments where you hope that a tiny bit of thread somewhere will catch on something.

So, without being an engineer I go with low center of gravity as my guess as to why Subaru do things few people expect them to accomplish.

Yes, it is a guess.

I can’t see what c of g has to do with off road ability. Not unless you are talking about being on severe lateral angles. In which case the more you lift a vehicle, Subarus included, the worse your c of g and propensity to fall over. Weight obviously plays a role. In water crossings, it can work for you. At other times it works against you.

psi and weight of car with that weight distribution plays so much on offroad. and my tires flex very good even with 2.1 psi in them i can see how they flex on sides even of tarmac. and then on offroad they just grip as hell there. imagine how good they would be at 1.8 psi or 1.5 psi.
weight in general works so great for less heavy cars as suzuki jimny it can just walk around pajeros or land cruisers any day on any surface with right tires and psi even with that small engine.

Rally said:

I can’t see what c of g has to do with off road ability. Not unless you are talking about being on severe lateral angles. In which case the more you lift a vehicle, Subarus included, the worse your c of g and propensity to fall over. Weight obviously plays a role. In water crossings, it can work for you. At other times it works against you.

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I know that I do not know... I am not an engineer. It is just a guess based on the fact that in a number of circumstances the OB did just as well as 4x4 rigs that, in those cases, should have had an objective advantage due to drive system and bigger tires--but did not. Yes, the Subaru spins but that spin never really affected me negatively and never was the scourge that wheelspin is for 4x4 rigs.

Of course, it may all be just in my mind since these are rigs seen on trail, not friends' vehicles, so I don't know what their drivers had been doing. Recently, I witnessed a TOyota trying to get up a biggish ledge without the offroad traction control and failed. I know what happened because I was close enough and on foot and I saw the driver reach for the A-trac button. Then the Toyota had no issues.

It is possible that lots of folks just like to power through stuff, making it look difficult and trashing the trail in the process.

BUT--I also know that low sedans can do surprisingly well in moderate snow around town.

I would like to hear from someone educated in a relevant field. As is, it is just my gut feeling that low center of gravity vehicles require less traction capability to get through the same stuff as tall 4x4s.

Partly because I don't see the weigh advantage. A 2dr Wrangler is the same or even lighter than a Subaru, depending on the specific models.

Center of gravity is very important !

Lets take two identical Toyota Prado's except that one has a 3" lift...the lifted one will be less capable on and off road because the weight in hight will always give more movements/instability, more weight transfer thus less grip.

For example, up a steep climb, the lifted Prado will have more weight on the rear wheels and less on the front wheels than the standard height Prado.

Then, everything is about compromise, because the lifted Prado will have better angles.

Have you corner weighted a lifter car against a non lifted car?

jf1sf5 said:

Center of gravity is very important !

Lets take two identical Toyota Prado's except that one has a 3" lift...the lifted one will be less capable on and off road because the weight in hight will always give more movements/instability, more weight transfer thus less grip.

For example, up a steep climb, the lifted Prado will have more weight on the rear wheels and less on the front wheels than the standard height Prado.

Then, everything is about compromise, because the lifted Prado will have better angles.

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This must be part of the story. Weight transfer increases while wheelbase decreases. This would explain why hugely built 2dr old Wranglers without lockers or offroad traction control can make things look difficult (2007+ have offroad traction control and the Rubicons have front and rear lockers standard).

Btw, I am keeping my Prado-based 4Runner stock except for AT tires, stock sized, and 3/16 steel plates under engine, transmission, transfer case, and gas tank plus on the mounts of the rear LCAs. If I ever go up, it will be 1.75/1.5, not 3 and not even 2".

I suppose the physics of moving rigs over undulating terrain are pretty complicated.

Rally said:

Have you corner weighted a lifter car against a non lifted car?

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Yes, a lifted car (lets say the Prado) is probably 8kg heavier ! 2kg per corner on a flat surface but probably 100+kg heavier on the rear axle on a 30° incline

A car is meant to move and thus dynamic is more important than static :iconwink:

So what were the before and after corner weights?

I think what people are talking about only applies when the car is on a hill. As the centre of gravity increases, the weight shifts towards the rear wheels while on a hill. Uneven weight distribution is bad for traction assuming all 4 wheels are on ground. Another advantage that adds to the low centre of gravity is that subarus tend to have the centre of gravity quite far forwards compared to other 4wds. (This does depend on model) So the result the weight will be closer to even on steep hills.

The amount a lift causes the weight to shift is

Lift height multiplied by tan(angle of slope)


If you are lifting wheels, you don't actually want the weight to be in the centre of the wheels, as that causes the car to rock about more o nthe balancing point and get diagonal wheelspin. Subarus front heaviness helps on level ground. But there's always this awkward slope angle where it rocks on the balancing point. And that slope varies between cars.

On another topic, there's lots of videos of the front and rear independent suspensioned Y62 Patrols absolutely destroying solid axled 4wd's such as Landcruisers offroad, despite being so heavy. Independent suspension is beast offroad.


Y62 tows 70 series up hill.
[ame="https://www.youtube.com/watch?v=jc3Jcuj8C-I"]Y62 dragging cruiser up hill at lcmp - YouTube[/ame]


Goes good in Subaru territory (sand) too. (Bit of language in this video)
[ame="https://www.youtube.com/watch?v=8TiazNPartY"]Y62 putting the rest to shame - YouTube[/ame]

ir depends could be same car one with full trunk furniture fridges and stuff and other with nothing and they would perform like different cars. we dont see that in videos how much they have stuff in trunk. at least front isf land cruisers likes to snap front axles very fast.

russians find mud so they put cars into it . Mitsubishi Montero, SsangYong Musso and Subaru Forester SH5 and russian Lada Niva 4x4 with lockers , larger tires with them.

[ame="https://www.youtube.com/watch?v=51Ef6MQfQ8c"]SUBARU FORESTER SH5 ? ???? ?? ?????? - YouTube[/ame]

looks like forester only have drove there with stock tires and stock heights and bumpers... i duno why ? to brake car ? but it tries still. just for mud you need at least some agressive tires and psi down. duno if anyone there lowered psi, they didint said .

again russians. why you put that white legacy there ? just why. on street mods with street tires. turbo forester looks better there. but if its manual that clutch must be burning there.
[ame="https://www.youtube.com/watch?v=W0mDg2SnL1c&t=1468s"]OFF ROAD SUBARU - YouTube[/ame]

is new jeep still hardcore jeep ?
[ame="https://www.youtube.com/watch?v=RPp1ICpzkBo"]We Take our 2018 JLU Rubicon Back to Moab & Finally Smash a Door! - YouTube[/ame]
it looks perfect for rock climbing.
at 5 min when womens tells you what to do with car ... haha xD
i would buy this car if i would be in US areas.

when you see how much those "advance" diffs cost its makes no sense for me. first that rear LSD diffs are not that made for offroading more on road better handling and stability and just helping with little slippages. traction control do more stuff and better .
best thing for me for any car is to see how it performs stock maybe with little help with tires and some lift , but no more mods. if car has more advance mods its no longer that car , it shoudnt be called that same name. hey i have forry that very capable offroad. ok but how much you payed for mods on it ? not same diffs and shocks on it. so its no longer same car

It depends where the border between a stock and a modified car is. My Forester is still a Forester because it still has a Subaru DNA with OEM modifications ( 1,59:1 low range, DCCD, EJ22, SVX axles, SG suspension links....) but I couldn't find long stroke suspensions so I had to find something else that for me is still in the Subaru philosophy.

A solid axle Subaru is no more a Subaru for me but the people who did this modification probably say it is ! Well, its everyones sensibility after all !