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  #181  
Old 16th May 2018, 12:08 AM
scalman scalman is offline
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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.
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  #182  
Old 16th May 2018, 12:37 AM
MiddleAgeSubie MiddleAgeSubie is offline
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Tire pressure and ground pressure are very different things though both are measured in psi.

As usual, I agree with @scalman,

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.
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  #183  
Old 16th May 2018, 01:51 AM
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Quote:
Originally Posted by MiddleAgeSubie View Post
Tire pressure and ground pressure are very different things though both are measured in psi.
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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  #184  
Old 16th May 2018, 04:00 AM
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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 voilą !
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  #185  
Old 16th May 2018, 05:35 AM
scalman scalman is offline
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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.

Last edited by Kevin; 16th May 2018 at 07:06 AM. Reason: off topic section moved
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  #186  
Old 16th May 2018, 01:04 PM
MiddleAgeSubie MiddleAgeSubie is offline
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Quote:
Originally Posted by duncanm View Post
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.
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.
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Last edited by MiddleAgeSubie; 16th May 2018 at 02:16 PM.
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  #187  
Old 16th May 2018, 03:20 PM
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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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  #188  
Old 16th May 2018, 03:23 PM
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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.
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  #189  
Old 16th May 2018, 04:40 PM
MiddleAgeSubie MiddleAgeSubie is offline
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Quote:
Originally Posted by Rally View Post
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.
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.
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  #190  
Old 16th May 2018, 05:12 PM
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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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