[whincup]

atari4x4 wrote:

whincup wrote:

When driving in the sand there is always a small pile of sand that you are constantly trying to drive over, the wider the tyre the wider this pile of sand is & the more resistance you will come across.

yes, but with narrow tyres that bump you are constantly trying to drive over is higher... you do sink in further with than you do with wider tyres...

[skelaaleks]

both types have +'s and -'s

Dont worry about it just go out and have fun with what you have.
The only thing that is going to stop you is the power of your motor!

I took my zook to fraser(thats the 1st reason i got it)
it had 31X10.5 muddies and i did it no problems.

Just run in 2wd unless you NEED 4wd (no point having the extra stress on your car all the time)

I (on purpoes) sunk my car in soft sand to the rails.
all i did was put it in reverse and it climbed right out.

[Gwagensteve]

It still amazes me that the wide tyre myth never goes away. The myth is really tied up with dune buggies and history. Dune buggies are amazingly light and run very soft, deformable tyres. for a sierra to have the same ground pressure as a sand car, it would have to have tyres of about 50"X24" and for it to perform the same way it would need over 400hp minimum.

By the same token, surely paddles would be awsome on a sierra! - well no, they'd suck - because the car can't possibly turn them fast enough to get the car up on top of the sand.

That's the key - Sand cars get up onto the sand - they are no longer pushing a wave in front of the tyre - like a boat planing. As those of you with boats know, it takes more power to push the boat through the water than it does to plane, even at a higher speed.

The important thing to understand about sand performance is that our cars are horsepower limited (that is, we have relatively low power to weight ratios) and sand saps HEAPS of power. It only saps power because it has yield - that is, the tyre displaces sand and pushes it ahead of the tyre. That absorbs energy.

Floatation is important on sand, but like every other type of driving, the shape of the footprint is as important as the size of the footprint.

A long, narrow, oval footprint is the most efficient to push along.

A wider footprint of the same length will provide more floatation, but this will be offset by more power being absorbed to move the car. In most cases, you'll find it diminishing returns to add width in sand once you've achieved the maximum height you can.

The contrast people are (correctly) making is between the SAME ground pressure with the variable being only the shape of the footprint. (long/narrow v short/wide) Sure, going from a 7" wide 30" tyre to a 10" side 30" tyre might increase performance, but going to a 7" wide 33" tyre might add more sand performance.

Like most other off highway driving, a bias ply tyre will provide the best performance in sand due to it's oval, flexible footprint.

Steve.

[SuziBlu]

Steve,

How much sand, soft sand driving do you do. Your explanation sounds fine, in theory, but its totally fukd.

I drive sand, love the stuff, very soft sand that 99% of vehicles bog to the diffs, I run Baja Claws, in effect sand paddles for a sierra, 31s, and am going to 33s, id go for 33x15s but the cost is prohibitive. 33 x12.5s will have to do.

You seem to have a fair knowledge of a mechanical nature, but in this you are very wrong, leave it alone as you are only showing how very little you know.

[gravity_powered]

In a nutshell:

On any tire you should be able to get where you want to go if you drop the pressure and keep your momentum up through the soft patches.

[atari4x4]

gravity_powered wrote:

In a nutshell:

On any tire you should be able to get where you want to go if you drop the pressure and keep your momentum up through the soft patches.

punch it frenchy

[gravity_powered]

atari4x4 wrote:

gravity_powered wrote:

In a nutshell:

On any tire you should be able to get where you want to go if you drop the pressure and keep your momentum up through the soft patches.

punch it frenchy

Call your mother!!!

[whincup]

ok... heres a question for ya: why air down if you want narrow tires?... wouldnt airing down make them wider? therefore defeating the purpose of narrow tires...

[atari4x4]

whincup wrote:

ok... heres a question for ya: why air down if you want narrow tires?... wouldnt airing down make them wider? therefore defeating the purpose of narrow tires...

all tyres become a lot LONGER when aired down...

have a read thru the measurements on this thread

http://auszookers.com/index.php?name=Fo ... 986#200986

these were alien's measurements, the width increased be 15mm & the length be 35mm

Tyre Make/Model: Simex Centipede ET
Tyre Size: 31x10.5r15
30psi, Length/Width N/A
20psi, Length/Width 260/215
15psi, Length/Width 260/215
10psi, Length/Width 265/220
5psi, Length/Width 275/220
0-2psi, Length/Width 295/230

& Red89's increased nearly 100mm in length while only getting 30mm wider

Tyre Make/Model: Simex Pedes
Tyre Size: 32x9.5r15
30psi, Length/Width n/a
20psi, Length/Width 229/205
15psi, Length/Width 229/210
10psi, Length/Width 262/221
5psi, Length/Width 285/228
0-2psi, Length/Width 325/232

next time you air down watch how much the length of the contact patch grows compared to the width

think about how a tank track works with it's really long contact patch.

[whincup]

atari4x4 wrote:

whincup wrote:

ok... heres a question for ya: why air down if you want narrow tires?... wouldnt airing down make them wider? therefore defeating the purpose of narrow tires...

all tyres become a lot LONGER when aired down...

have a read thru the measurements on this thread

http://auszookers.com/index.php?name=Fo ... 986#200986

these were alien's measurements, the width increased be 15mm & the length be 35mm

Tyre Make/Model: Simex Centipede ET
Tyre Size: 31x10.5r15
30psi, Length/Width N/A
20psi, Length/Width 260/215
15psi, Length/Width 260/215
10psi, Length/Width 265/220
5psi, Length/Width 275/220
0-2psi, Length/Width 295/230

& Red89's increased nearly 100mm in length while only getting 30mm wider

Tyre Make/Model: Simex Pedes
Tyre Size: 32x9.5r15
30psi, Length/Width n/a
20psi, Length/Width 229/205
15psi, Length/Width 229/210
10psi, Length/Width 262/221
5psi, Length/Width 285/228
0-2psi, Length/Width 325/232

next time you air down watch how much the length of the contact patch grows compared to the width

think about how a tank track works with it's really long contact patch.

ok, thanks. i was actually genuinely asking, since logic to me says bigger surface area is better, and i havent ever compared the 2...

[MacDaddy]

I was told this once, and it really helped me understand... think of a gravel road, with lots of pea sized rocks, a wide tyre will just roll and spin on the gravel, and will have little traction, where as a thinner tyre will cut through the gravel and have more grip, length of tyre area, thin, will work better on a loose surface, than width of tyre area, wide...

[fordem]

Think about this - how far down do you need to go in said loose surface before you find enough grip to move forward - gravel & sand are different.

[skelaaleks]

Just go hard u's are forgetting that with a zook if you punch it hard enough you can do anything

[woody1]

Do what I do.
Let ya tyres down (for sand) to at least 14, 15 PSi.
If ya get stuck let em down a little more. etc etc etc.
Just dont turn to sudden though.

If ya still get stuck after this by a hovercraft.

Every time I drive onto Lavis Lane at Stocko
I come across someone that is stuck coming out.
Some people think it's funny to air up before they get off the beach so
when ya hit Lavis it's like driving over a midgets BMX track.
Bloody see sawing all the way.

Let me know when ya thinking of going back to Stocko
we should all meet up. Just an idea.

[2stroker]

[quote="Gwagensteve"]It still amazes me that the wide tyre myth never goes away. The myth is really tied up with dune buggies and history. Dune buggies are amazingly light and run very soft, deformable tyres. for a sierra to have the same ground pressure as a sand car, it would have to have tyres of about 50"X24" and for it to perform the same way it would need over 400hp minimum.

What do you mean by this, most dune buggies were cut down VW's, they did not have any more clearance than a decent 4x4 and did not have heaps of power, their ability came from having engine over the back wheels and big tyres

[Highway-Star]

I can't beleive some of the garbo I've read in here!
A stock Sierra on 205's will eat up soft sand (assuming you don't drive like an imbecile). If you think you need lift, different tyres, blah blah blah, then calm down, and drive a stock one on the beach, they work fine!

Personally I think the one biggest improvement you can make to a predominantly sand driven car would be to fit an automatic gearbox; but it really is not required, just makes it idiot proof

[Gwagensteve]

2stroker wrote:

What do you mean by this, most dune buggies were cut down VW's, they did not have any more clearance than a decent 4x4 and did not have heaps of power, their ability came from having engine over the back wheels and big tyres

A cut down VW will only weigh 500kg or so, and run a 10X15 rear tyre. That's less about 1/2 the ground pressure of the average sierra on 31's. Sure, it only has 60 HP or so.... but so does a stock sierra. (67, to be precise)

SuziBlu - there was no need to unload like that. Im' sure your car performs very well on sand, but you missed my point. Take the same ground pressure you have now with 31's, but make the footprint longer and narrower (still with the same physical area, just a different shape)and the car will perform better. As you continue to reduce ground pressure, you want to reduce it by adding length to the footprint, NOT width.

PS, have you ever tried your claws backwards in sand? I think you might be surprised how well they work.

Steve.

[SuziBlu]

Steve,

Ok sorry, I was a bit out of line. But, seriously, I am a sand driver, and, narrow is not at all what is the go.

Sideways at 60k or so, with wide, is cool, with narrow, bugger that. Talk about roll.

Mud, yes, get down an dirty, sand, the bigger the footprint, the lighter the load, and so, the more float you have, and so, the better off you are.
Even mud drivers are in a state of indecision, narrow gets down to the hard, wide, floats.

IF you want to speak of diameter, then we can speak equally, but not on width, I am fully of the understanding that the bigger the footprint, the better. Its all about, weight per square inch of surface area.

As we air down, we gain mostly length, we both agree, but also we gain in width, and that is where we differ, wide and long wins the race, narrow and long, without huge diameter, is not so good.

Where "real" 4wbys will dig themselves to a short grave, suziblu will, in 2wd, coast up, hardly leaving a track, and show off, larfin at the "real"4wby, and pull it out, very easily.

I stand firm, giant tread pattern, deep tread, low pressure, wins in sand every time.

[daniel_111]

WIDER=BETTER, i live right behind stockton sand dunes, and my dad has lived here his whole life so that = alot of sand driving experience, have tried the skinnier tyre and yes it still worked fine, but not as good as wider and it just made the car more unstable when turnin, oh and all terrains get the thumbs up for sand driving, they seem to work the best for me even though im just running standard size road tyres at the moment, and still have no problems on the dunes, just gotta rev it more.

[Benz]

hahaha if i read this b4 i went for a drive at the beach i wound be so confused!

i would suggest.... just air down your tyers
and to take a shovel and someone to push you when you get stuck!

[whincup]

Benz2369 wrote:

i would suggest.... just air down your tyers
and to take a shovel and someone to push you when you get stuck!

yea look, aside from all the disagreements (which really come down to each persons individual driving style and personal opinion) any tyre should be fine on a sierra if its aired down... seriously, there is literally NO fourby that will come close to matching a sierra on sand, regardless of the tyres...

[daniel_111]

whincup wrote:

Benz2369 wrote:

i would suggest.... just air down your tyers
and to take a shovel and someone to push you when you get stuck!

yea look, aside from all the disagreements (which really come down to each persons individual driving style and personal opinion) any tyre should be fine on a sierra if its aired down... seriously, there is literally NO fourby that will come close to matching a sierra on sand, regardless of the tyres...

Amen!

[2stroker]

Gwagensteve wrote:

2stroker wrote:

What do you mean by this, most dune buggies were cut down VW's, they did not have any more clearance than a decent 4x4 and did not have heaps of power, their ability came from having engine over the back wheels and big tyres

A cut down VW will only weigh 500kg or so, and run a 10X15 rear tyre. That's less about 1/2 the ground pressure of the average sierra on 31's. Sure, it only has 60 HP or so.... but so does a stock sierra. (67, to be precise)

I don't know where you got your figures but a Baja style VW with choped guards and fibreglass panels still weighs over 800kg, and has around 45KW. Obviously a full glass manx bodied one would be a fair bit lighter and could be running a combie engine that would be more powerful. But I think saying that a suzuki would need 50" tyres and 400HP to be comparable is a ridiculas statement.You were talking "dune buggies and history" and being old I was part of that history, back in the day that was all they did, buy a fibreglass panel kit, some wide rims and big tyres for the back, a donaldson air cleaner, engine cage and extractors and away you went.

[SuziBlu]

Here is a pic of suziblu, in reasonably wet firm sand, an wishing she could have skinny tyres like the bloke who went before.

[MacDaddy]

SuziBlu wrote:

Here is a pic of suziblu, in reasonably wet firm sand, an wishing she could have skinny tyres like the bloke who went before.

Hmmm... looks like your wheel alignment is out there...

[SuziBlu]

er, ????

She is scoring the fronts pretty bad, but, how on earth did you see that.

[MacDaddy]

SuziBlu wrote:

er, ????

She is scoring the fronts pretty bad, but, how on earth did you see that.

I have a keen sharp eye, i notice things... looks like you got nearly 5 degree's positive toe there ( toe in )

[Gwagensteve]

SuziBlu wrote:

Here is a pic of suziblu, in reasonably wet firm sand, an wishing she could have skinny tyres like the bloke who went before.

Let's be honest though, what did the "car that went before" weigh?

Those 10.5's aren't exactly wide though - but it they were a couple of inches taller you'd be amazed by the performance improvement.

2Stroker - I'd take 67Hp (that's 45Kw)in an 800KG car over 67Hp in a 100Kg in sand - especially with the weight distribution of a VW. Take 200KG out of an average sierra and it's sand performance would improve substantially.

I never really explained the "history" part of my comment - it was that 10R15's were about all that was available other than rock hard, square and umpteen ply rated 7.50 16's back in the day. In fact many early 10R15 tyres were actually sand tyres, like the Armstrong commando - they have a tread pattern almost dedicated for sand.

Steve.

[2stroker]

Yeah don't get me wrong Steve I agree with you bigger diameter and longer footprint is good. My extremely light fibreglass LJ with 80kw is awesome on 700/16's (i think you meant 67hp in a 1000kg).

[daniel_111]

SuziBlu wrote:

Here is a pic of suziblu, in reasonably wet firm sand, an wishing she could have skinny tyres like the bloke who went before.

why?? those tyre would of been fine, just coz its not diging in