<span class="highlight">Tyre</span> <span class="highlight">Pressures</span>

Submitted: Monday, Jul 31, 2006 at 14:18

ThreadID: 36310 Views:2311 Replies:12 FollowUps:4

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GoneTroppo Member (FNQ)

How's this for setting people up for failure?

Had some people working at our farm cleaning up cyclone damage last week.
They were using a 100 LC with a tray conversion, rented from one of the 4x4 rental outfits.

I had to go for a drive with the foreman to a paddock at the back of the property along some rutted, muddy tracks and moderate hills. He was struggeling as well as bouncing all over the shop.

And yes we promtly got bogged in some soft mud.
He was looking pretty worried and commented that the other crews were always getting bogged as well.

Checked the hubs were locked , (OK obvious but often overlooked)

Looked at the tyres, a mixed bag of 750/16's Road Track major type tread about 40 to 50% worn but should have been OK for the conditions.

Inflation? In a word, absobloodylutely rock hard. (I did not have a tyre guage with me)

We let a lot of air out until we got some bagging, hopped back in the car and drove out.

Back at the shed we checked pressures before sending them home on the highway. The let down ones were still around 30 and 35 psi. One front tyre which the guy admited to not having let down much was still showing 65psi.

At a guess therefore they were all at 70psi+ to start with.
So I explained a few things to him sent him of with 35psi.

Couple of days later I caught up with him again, he said the car was much better on the road, much more comfortable and he hadn't been bogged again, and he was going to show the other crews all about it.

Can anyone think of a good reason for sending people out with that sort of pressure in the tyres?

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Reply By: Rokkitt - Monday, Jul 31, 2006 at 14:40

Monday, Jul 31, 2006 at 14:40

Would it improve fuel consumption? less rolling resistance on the tyre???

AnswerID: 186269

Follow Up By: GoneTroppo Member (FNQ) - Monday, Jul 31, 2006 at 14:53

Monday, Jul 31, 2006 at 14:53

I can't see the rental mob caring.

BTW forgot to mention that all the tyres were wearing significantly more in the centre than the shoulders (as you would expect)

FollowupID: 443311

Reply By: Member - Chris R (NSW) - Monday, Jul 31, 2006 at 15:14

Monday, Jul 31, 2006 at 15:14

Dear Toyota supplied my troopie new with over 70psi. Story was that they are imported with high pressure for transport and then supposed to be adjusted... but I wonder. Could it be that tyre pressure was NEVER adjusted?

I once assisted a lady at service station having difficulty adjusting mercedes tyres. She was aiming at the tyre manufacturers max inflation pressure printed on tyre wall.

Cheers

Chris

AnswerID: 186276

Reply By: Robin - Monday, Jul 31, 2006 at 15:19

Monday, Jul 31, 2006 at 15:19

There could be a very good reason GoneTroppo.

35psi could be under the pressure required for that car to carry that load at
100kph and it could therefore cause an accident.

It is most likely that 35psi is ok at 60kph though.

7.5X16 normally are rated to 85psi and some landcruisers so fitted are plated at
around 48 to 55 psi so tyre doesn't go bang.

That car is apparently converted so maybe it is re-plated for tyres , and a check there might help sort out whats required.

Robin Miller

AnswerID: 186277

Reply By: Member - Phil G (SA) - Monday, Jul 31, 2006 at 15:24

Monday, Jul 31, 2006 at 15:24

Pulled a rental 4wd out of a sandy river bed in Central Aus once - had 50psi in the tyres, which was double the manufacturers pressure. I think rental companies believe that tyre failure is less common and also that punctures are not their responsibility.

AnswerID: 186279

Reply By: Trevor R (QLD) - Monday, Jul 31, 2006 at 17:16

Monday, Jul 31, 2006 at 17:16

Could it have something to do with getting more mileage from the tyre when it is at higher pressures?

Trevor.

AnswerID: 186312

Reply By: teabags - Monday, Jul 31, 2006 at 17:21

Monday, Jul 31, 2006 at 17:21

Recently replaced tyres on NM Pajero with standard sized 265.75/16 AT's. Mitsubushi recommend 29psi. Tyre rated maximum pressure 35psi. Dealer (very large chain) said to run at least 40psi.. What would this do to your insurance if you had an accident, running 5psi over manufacturers maximum. When I checked the tyres just up the road from the dealers they had 48psi front and 52 rear.
Why do these clowns think they know so much more than both the vehicle manufacturer and the tyre manufacturer.
Always found that running tyres at manufacturers recommended pressure and keeping wheels aligned I get even wear right across the tyre.

Alan

AnswerID: 186315

Reply By: Max - Sydney - Monday, Jul 31, 2006 at 20:12

Monday, Jul 31, 2006 at 20:12

More often than not, when I get new tyres, the bloke says: "What pressure do you want?" I say: "The placard says 30 psi - put in maybe 32". They often lecture me and say something higher, in which case I say "OK".

In any case, when I drive out, I stop around the corner and check them. Invariably, they are all different and range from 45 to 60 psi. I let them down to 32.

I think tyre fitters are trained to never drop the pressure after seating the beads! Its been happening since 1990 (first time I bought 4X4 tyres) to my memory. Grr.

Max

AnswerID: 186360

Follow Up By: D-Jack - Monday, Jul 31, 2006 at 20:38

Monday, Jul 31, 2006 at 20:38

Problem with that theory is I can set my beads on 16x 7s running 245/75/16s Cooper ATRs, with less than 20psi easy, sometimes it is 10 or less, using a blue tongue.

FollowupID: 443415

Follow Up By: Max - Sydney - Monday, Jul 31, 2006 at 20:42

Monday, Jul 31, 2006 at 20:42

So why do the blighters do it then?

FollowupID: 443416

Reply By: HGMonaro - Monday, Jul 31, 2006 at 20:42

Monday, Jul 31, 2006 at 20:42

same deal... straight from Toyota, presures all over the place and way too high. I also had to remove their number plate frames and sticker I asked them not to put on the car in the 1st place. What do they do for their 'dealer delivery fee'? nothing I suggest! I did buy a Holden once and the salesmans moaned and groaned about not having his stickers on it, but did supply the car as requested without advertisments.

AnswerID: 186365

Reply By: johannagoanna - Monday, Jul 31, 2006 at 20:46

Monday, Jul 31, 2006 at 20:46

Another reason that nobody has touched on here, is that the trye gauges on the pumps are more often than not, very inaccurate. Could account for a lot of errors!

Next time you pump up your tyres check them with your own guage, and you will see how inaccuate they can be!

Jo

AnswerID: 186366

Follow Up By: teabags - Monday, Jul 31, 2006 at 21:40

Monday, Jul 31, 2006 at 21:40

Always use my own digital gauge. Those service station ones get such a hard life that most are worse than useless.

FollowupID: 443447

Reply By: slammin - Monday, Jul 31, 2006 at 22:31

Monday, Jul 31, 2006 at 22:31

Ah Gone troppo you've hit my pet hate on the head.

I drive lots of NT Govt 4wd's all sizes and makes for Dept. Ed. , Ambo's etc and the pressure is always at 60+psi rear and 45+psi front. They even have new stickers above the wheel well that states it is the recco psi. They come back even harder after a service.

Good for hwy driving and saving tyre wear but deathtraps on the dirt and easily bogged. I have come across 3 seperate vehicles that have rolled. In each case there were fractures but luckily nothing worse. These were Govt. vehicles that I saw first hand on their sides and guess what rock hard tyres resulted in bouncing all over the road, bit of a rough patch they get side ways and it's roll over red rover.

When I get newbies we give them a basic 4by heads up which has helped. Nobody in my team has had any accidents in 7 years but if we compare the numbers through the area and we are a minority. I have raised the issue and come up with no answer for the high pressure recco. I beleive it is for lower tyre wear and better handling at speed on bitumin. I also beleive they feel if the car handles like bleep on dirt the drivers will slow down.

The govt only provide 4wd training to staff who drive regularly as part of their job.

AnswerID: 186397

Reply By: Member - Oldplodder (QLD) - Tuesday, Aug 01, 2006 at 08:21

Tuesday, Aug 01, 2006 at 08:21

Maybe the rental company puts the tyre pressure high for a rough ride, and easy bogging. That way people are less likely to thrash the cars, and they are setup to carry full load?

AnswerID: 186441

Reply By: David from David and Justine Olsen's 4WD Tag-Along - Thursday, Aug 03, 2006 at 20:49

Thursday, Aug 03, 2006 at 20:49

Anyone who has ever driven a government hilux ute will know how frightening they are on rough roads when the rear tries to overtake the front. I used to always let my tyres down after a trip to the "mechanic" when I drove a Govt vehicle.

AnswerID: 186990