Tyre construction: Ligth truck vs passenger type???

Submitted: Friday, Feb 10, 2006 at 15:02
ThreadID: 30638 Views:2289 Replies:7 FollowUps:6
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Hi everyone,

could someone please enlight me about this? From what I understand LT construction is more robust since designed to work with high loads on a constant basis. Hence they are less prone to punctures. On the flip side they are more prone to overheating which is compensated by running them at higher pressures. The last bit is the one I am struggling with:
How much pressure are we talking about for same size tyre? Depending on the difference you would spend a lot more time pumping them back up after a stroll in the sand. Does that also mean that when driving in sand with LT tyres deflated they are likely to overheat and get damaged?
Thanks, SLY.
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Reply By: boo boo - Friday, Feb 10, 2006 at 15:58

Friday, Feb 10, 2006 at 15:58
I run Hankook LT 235/85R x 16 on my troopy and have 35psi fronts and 40 in rears. I do mainly highway travel to and from work ie 160 km per day and have no trouble from overheating. Tyre wear is OK as long as I rotate every 10k. I don't think my tyre pressures are high. Don't know about about sand.
AnswerID: 154320

Reply By: Member - MrBitchi (QLD) - Friday, Feb 10, 2006 at 16:11

Friday, Feb 10, 2006 at 16:11
LT is more robust. LT tyre generally has more plys than passenger rated tyre.
This means it's stiffer in the sidewalls and stronger across the tread, making it less prone to punctures and sidewall damage.

In normal use heat build up is not a problem if you're running at 'normal' pressures.
Personally I run my LT Coopers at 38psi all round on the Pajero. This is the same pressure I used to run the passenger constructed Yokohama OEM's and I've not noticed any difference in tyre temperatures.

Any tyre will heat up when run for long periods at low pressure. That's why you should allways keep the speed down and pump them up again as soon as practical. I've never suffered any damage from low pressures in the sand, on either type of tyre.

I'd suggest that most tyres that are damaged by prolonged sand driving (Simpson desert for example) can usually be attributed to either the tyres age, causing hardening of the rubber and fracturing of the sidewalls, or simply being run at too low a pressure at too high a speed for too long....
AnswerID: 154322

Follow Up By: slyonnet - Friday, Feb 10, 2006 at 16:19

Friday, Feb 10, 2006 at 16:19
Thanks John,

I think the article I read was a bit over the top when saying LT tyres would need to be run at higher pressure. As you said pending you're not driving too fast for too long at low pressure and are not too harsh on them LT tyres should not suffer any more damage than a passenger type tyre. In fact I now believe they ar probably a better option since they have more plys and are less prone to puncture and sidewall damage (again that's if you drive them appropriately).
Thanks again, SLY.
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FollowupID: 408304

Follow Up By: JW - Friday, Feb 10, 2006 at 16:22

Friday, Feb 10, 2006 at 16:22
John,
You told me once before that your sand flag was a telescopic squid pole. Did you get it from a tackle shop in Brisbane? I am soon going to be in Bne for a few weeks and I thought I may have more luck there rather than in central Qld.
Thanks.
Jon W
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FollowupID: 408306

Follow Up By: Member - MrBitchi (QLD) - Friday, Feb 10, 2006 at 16:37

Friday, Feb 10, 2006 at 16:37
JW,
My local tackle shop ordered it in for me. Not a common item in QLD but readily available in Vic. Any tackle shop that has a Shakespeare catalogue should be able to get you one, Cost $50 from memory.
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FollowupID: 408309

Follow Up By: JW - Friday, Feb 10, 2006 at 16:42

Friday, Feb 10, 2006 at 16:42
Thanks John. I'll try a BCF store when I'm in Bne. Knowing the brand will help.
Jon W
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Follow Up By: Vivid Adventures - Friday, Feb 10, 2006 at 17:25

Friday, Feb 10, 2006 at 17:25
Hi John,

I looked on www.shakespeare.com.au and they have a couple there - I guess you have the Ugly Stick brand?

Can you pls tell me how you mounted it?

Many Thanks
Andrew
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FollowupID: 408324

Follow Up By: Member - MrBitchi (QLD) - Monday, Feb 13, 2006 at 11:29

Monday, Feb 13, 2006 at 11:29
Andrew, I'll check tonight and see if it's got a model number. Seem to think it's the "Wonderpole".

To mount it I just used some heavy duty ocky straps (the flat rubber ones) and strapped it to the spare wheel.

!MPG:3!
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FollowupID: 408666

Reply By: Member - Oldplodder (QLD) - Friday, Feb 10, 2006 at 17:20

Friday, Feb 10, 2006 at 17:20
Run 235/85/16 LT '10 ply' on the pajero.
Prefer the '8 ply', but harder to get.
Load rating is about 1000kg per tyre, so tyre is no way over loaded!
Don't be fooled by the ply rating. There are not that number of plies in the tyre.
There is still only 2 or 3 in the side wall, and maybe 4 in the tread.
Just a lot more rubber. That is why these tyres can weigh up to 40kg each, depending on size.
Just that the load rating is referring back to the old truck cross plies where they used to run 8 or 10 or 12 or 16 plies for heavier load ratings.

Max tyre pressure for my tyres is 80psi.

I usually run 40 psi on the bitumen empty. Still get even tyre wear.
Go to about 50 on the rear and 45 on the front loaded. Found these pressures by trial and error by checking temperatures and using the 4lb rule.

Yes, the ride is firmer.

Tracks I drop to 30 to 35, and keep speed under 90km/hr.

Sand I usually run 20 to 25. Keep speed down to 70/80, depending on pressure and dryness of sand. Firm sand I run 30.

If I run these tryes on bitumen at sand pressures they get very hot very quickly, even at 60km/hr.

But then, i haven't had a puncture, even in gibber and desert country.
(Beat that breaks my good run!)
AnswerID: 154340

Reply By: Graham & Ann - Friday, Feb 10, 2006 at 21:18

Friday, Feb 10, 2006 at 21:18
An explanation re differences P and LT tyres can be found here.
http://www.toyo.com.au/tech_info_intro.html
and open pdf bulletin No. TTT-127 it is part 4 of a series re Inflation Pressure and gives a bit of an insight into why LT tyres need more PSI than P tyres to carry same weight.

cya
Graham
AnswerID: 154381

Reply By: Mulga Bill - Friday, Feb 10, 2006 at 22:08

Friday, Feb 10, 2006 at 22:08
Agree with the above overall - LT is more robust than passenger as a generalisation, but the trade-off is that the LT transmits more road vibration up to you ! Passenger tyres, like my original GY Wranglers on the Jack (not the off-road Wrangler) have a ridiculously thin shoulder - one that gives a limo like ride, but are a dead set disaster on the stones. My BFG's offer relative peace of mind, while we bump along !
AnswerID: 154393

Reply By: Mulga Bill - Friday, Feb 10, 2006 at 22:12

Friday, Feb 10, 2006 at 22:12
forgot to say, re heat levels..... I often feel the tyres when out of the vehicle, to get a picture of what we are doing - whether the pressures are up for hardtop, in the middle for stones, or way down for sand, we haven't had any heat extremes yet - but we do tend to take it easy.........
AnswerID: 154395

Reply By: Member - Collyn R (WA) - Saturday, Feb 11, 2006 at 13:12

Saturday, Feb 11, 2006 at 13:12
For the record - a tyre's 'ply rating' has not (for decades) indicated the number of plies in its construction.

It is essentially a marketing term that indicates approx wall thickness.
Collyn Rivers
AnswerID: 154443

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