a little actual driving advice please ;D

I am curious to know whether a reduction of tyre pressure on steep rocky tracks would maybe help with traction and reduce the risk of sidewall punctures?? I'm not talking sand pressures here....... i run my tyres at about 40 psi.... so would say dropping it to about 20 psi help any? And by rocky i mean loose rocks and dirt.

[BLU-125]

To give sensible advice would need to know what size you are running. Generally speaking lower pressures provide a huge improvement in traction at the expense of exposing radial sidewalls to damage, hence the development of bias (or cross) ply off road tyres such as Swampers & Claws which have walls as thick as their tread face.

[baby_troupe]

Depending on the trails, I generally use 24psi offroad, but if it gets loose, I drop down to about 15 - 20, depending on the terrain & what tyres I am using.
If I did it on my Bridgestones I would be encouraging a sidewall puncture as the sidewalls on these are baggy. (moreso than my BFG Muddies)

The tyres i use are pretty much stock 225/75 R16 They are commercial rated, the ply rating i can't remember and i'm too lazy to go outside and look hehe ::) I thought that a lower pressure might decrease the chance of sidewall puncture due to the fact that the sidewall would give way a little to rocks and sticks..... The whole tyre thing interests me and i'm keen to learn a lot more.

[HSV Rangie]

Dropping your tyre pressure will greatly enhance the traction available to you.

at the same time lowering presure exposes the side walls to damage, but often negated by the fact that you will not be spinning wheels which cuts the tyres.

20 psi is pretty good for most off road driving conditions eperience will thenallow you to lower more as required.

Michael.

[BLU-125]

If you are using 225/75R16's, they are probably American. If they are, they will probably be 8 or 10 ply rated with fairly straight walls.

This will allow you to use low tyre pressures to your advantage as the tyres will be proper light truck construction and will cop a fair bit of abuse. If you need to, 10 or 12 psi would be safe to clear an obstacle, but 15/18 should normally be low enough for low speed, loose, rocky tracks.

Don't forget to increase pressures when you are travelling at normal road speeds.

If your tyres are Korean 225/75R16's, add 4psi to all of the above.

That doesn't mean that the Koreans aren't good tyres, it just means we see more tread (or case) separations from Asian tyres run at low pressures.

These tyres are American..... Firestone. Lower pressure makes them bulge a little, but it doesn't seem too bad though

[PaulB]

Reducing tyre pressure will improve traction. See recent article in magazine. It will also make for a smoother ride at a given speed as the tyres will have more give. And here lies the compromise. Reducing tyre pressure causes the tyre to have more give. This can allow the side wall to get nipped between rock and rim if hit at too high a speed. However as you have more traction you don't need to travel so fast as momentum is less of an issue and you won't spin your wheels so much. Also if you travel at high speed on soft tyres they will over heat and disintegrate, usually on a corner.

Summary: if going gets slippy let tyres down and drive slower. The figures given above, by blu125, look good.

REMEMBER never corner hard with low pressures especially on sand. Tyre comes off rim, rim digs into sand and car goes over. We had two cruisers go over last weekend in our area and at least two deaths in the last two years from people doing donuts on the beach. Some people never learn.

[Humpy]

its hard to learn when your dead

[baby_troupe]

REMEMBER never corner hard with low pressures especially on sand. Tyre comes off rim, rim digs into sand and car goes over. We had two cruisers go over last weekend in our area and at least two deaths in the last two years from people doing donuts on the beach. Some people never learn.

Beadlocks can help prevent that from happenning.
I have been reading about these & thinking about getting some in a year or so (other things have priority at the moment)
Secondair type are available from www.offroadshop.com.au for under $200 each.

[PaulB]

Beadlocks will stop the tyre coming off the rim. BUT their main purpose is to prevent it SLIPPING on the rim. Hence all the serious rock hoppers have them because they run big tyres at low psi (<6 sometimes). Unfortunately you can still dig a rim into soft sand even without the tyre coming off. Basically the golden rule is 'IF YOU WANT TO TURN ON THE BEACH SLOW DOWN FIRST'

If you really want to do donuts buy a playstation.

PS check the legality of beadlocks in your state before the boys in blue use you as a tax break for the general public.

[Wilesy]

The other weekend, I went 4 wheeling with a bunch of my mates at ZZ.

I have never been a fan of dropping my pressures too much except in soft sand and usually don't go lower than 22psi in severe rock climbing territory. The diff lock keeps me out of most of the trouble.

One thing to remember that the lower you go, the lower your body goes towards the ground, therefore reducing valuable clearance.

What's the use in spending all of that extra money on going up 50mm, only to drop down 30mm when you air down too much.....

Anyway, back to my story.... :P

All of the blokes that were with me, convinced me to drop them to 18-20 just to see if there would be any significant advantage in my own opinion in running even lower pressures than what I am used to running, after a debate on the subject before heading off.

Well it did….there was definitely a big difference in the way the vehicle handled, particularly during the good grade dirt tracks, (In between the severe stuff) which I was forced to drive pretty slowly around the bends, as the handling was fairly unpredictable to say the least. >:(

For the first time ever, I came home with rips and gashes all over the sidewalls of my new BFG's, and copped a dent the size of a fist in my rear diff, which I was convinced I should have cleared…..and even dropped a rut which I should have straddled but the tyre allowed the vehicle to squirm and fall into…Mmmmm >:(

Maybe the extra 4psi down may not have had a lot to do with it, though I won't be doing that again......

I should have stuck to my own advice and done what I thought and knew was right.... :-\

That is one thing that worries me a little, until such time as i can do a suspension lift :-\ My Rodeo doesn't have a lot of clearance now, and if i dropped the pressure in the tyres on it, it would easily sink 2" I have worked out how to get the 3" lift i'm told i can't do, i just need the time to actually do it.

im a firm beleiver in dropping my pressures, im sure i lose a little clearance but running 33' tyres whilst some others are running 31's i dont think im at any real risk of much damage. the tyre size has made up for that drop.
with the hilux being so light in the rear i have ran 8psi in the bush before without beadlocks and 20 up front have not yet punctered or popped a bead yet. have scratched the side walls a bit though.

[Wilesy]

I really don't think there is a blanket answer to this one.

What pressure you use is mainly determined on the type and weight of the vehicle you are driving.

Dropping your pressures to 18 psi in a Hilux without any weight in the tray, shows that the tyres are still inflated to a fair degree, where as if you drop the pressures on my vehicle for arguments sake being a Patrol carrying 130 litres of fuel on board at the back 18 psi shows the tyres to look positively flat.

Everyone needs to determine their own pressures themselves, with only a rough guide to what everyone else uses to go by.

No-one else suffered any damage on the day we went out but me….. >:(

Then again, I did have the heaviest car in the pack. :-\

See, you learn something new every day. Doesn’t matter how many years experience you may have….

[wooders]

On my TJ with my regular tyres 35" Muddies I'll generally drop to 12 PSI when offroad...yes they have a few more suffs - but it makes it so much easier on the rest of the vehicle that I'm happy to trade-off....
With the 36" swampers I have on beadlocks I'll generally run those at about 8psi - but I have gone as low as 4psi...

Anyway IMHO airing down reduces the wear on the vehicle AND the trail.

[Wilesy]

Yeah,

Though you do have a very light vehicle though Wooders.

The back end you could just about lift off the ground on your own. 8)

[wooders]

it's not THAT light...It's just not a bus ;)

[oiler]

I run Cooper STs 265/75 16 on 16/7 Prado rims on my 80 series and until recently rarely lowered my pressures except for sand. I'll go as low as 16 on sand but no lower than 25 on any other surface. I get increased traction, less track damage and if the compressor breaks I can still travel home at reasonable speeds.

[2 BRUTAL]

airing down a bit also takes the rigidity out of your tyres so they are more inclined to roll over an object rather than bounce off it. there was a story a while ago somewhere about a group doing a dessert crossing and they had very high tyre pressures because the ground was very rocky they thought they'd keep there pressures up. but they suffered a lot of punctures because the tyres were so stiff they wouldn't roll over the rocks rather they would get stabbed because the tyre wouldn't give and flex any. ;)

[taziiy]

i drop mine down to 12 -15 i find it takes a lot of pounding out on the corrigated dirt roads too

[BLU-125]

If you are a city dweller who chooses to go to God's country, (central Oz), go to any Pub and ask the locals what pressures THEY use. If you have a copy of the Australian Tyre & Rim Association Handback with you, you will probably find that the locals use pressures that are slightly lower than the engineers say they should use, but a hell of a lot lower than what city drivers will have been told to use.

If you drive on well maintained, sealed roads all the time, too high a pressure isn't really a problem & you may coax an extra few k's out of your boots. Impact damage is, however, if you use too high a pressure, almost guaranteed on our poorly maintained country roads.

The trouble is that in this era of product liability - and the speed that litigation is initiated - means than any advice you get about pressures is so conservative to be meaningless, esp. as most city tyre dealers have no idea about RV tyres.

[oiler]

I was running a 4wd course in Townsville last year and we were climbing a hill out the back of town. Most vehicles made it up without trouble and the first vehicle to get stopped was a Troopy. He was digging ditches and sliding all over the place and after a couple of runs at the hill I winched him up as a demo. I thought the trouble may have been the 750/16s fitted but imagine my surpirse when I asked if he had lowered tyre pressures as recommended. He had left them at his normal road pressure of 70psi! It must have been like riding on thin strips of steel.

Like verything it's up to what you want.....

Airing down to 20PSI in a 31" tyre may for example make it as capable as a 33 @ 30psi....(dunno it's only an e.g.)


But obviously sidewall damage is a concern. If your in greasy hard surfaces with not much chance of damage then less is better as you tend to not dig up tha surface as much so next time you don't NEED 33's....

There is also pushing a tyre off and getting stuck completely...


Higher pressures, although protecting your tyres may cause more driveline problems(bucking bronco syndrome), excessive wear on the tread area(get 'em smokin), and more damage to the local habitat(digging trenches)....

[ferremit]

what kind of tires you running Roe?

Our lux runs firestones, and im sure as hell that they are a NZ company, who was bought out by Bridgestone.

Had both the Firehawk RMTs and the Firehawk RVs (current fitting) on the lux, both have performed awesomely. The RMT is a very good halfway between a AT and a Muddie- good mud performance, yet good road manners and wear rates, and the RV is a VERY aggressive AT tread- got me up a clay hill where my mate struggled with his BFG AT's

Never have aired down since fitting the 15x8 rims on the lux, never needed too.



and for the record, because we were driving 3.5 tonne land cruiser utes, with around 2 tonne over the rear wheel, airing down 20 PSI made our rims touch the ground- thats from 55-35psi :o

I am curious to know whether a reduction of tyre pressure on steep rocky tracks would maybe help with traction and reduce the risk of sidewall punctures?? I'm not talking sand pressures here....... i run my tyres at about 40 psi.... so would say dropping it to about 20 psi help any? And by rocky i mean loose rocks and dirt.
ABSOLUTELY, REDUCE THEM TO 20-25PSI. IT WILL INCREASE TRACTION NOTICABLY AND ALLOW YOUR TYRES TO FLEX AROUND ROCKS

[Jys5428]

Ever noticed how the extra lugs and tread on the outsides of specialised tyres like the MickyT's and X-Terrains bag out when you let them down. It's there for a reason. If your tires arn't designed to drive flat, dont let them down so much that the side walls are at risk!
http://www.procomp.com.au/Images/PcImg_PcXTerrain_AngleSpecLrg.bmp