Stock tyres 2015 GXL 57psi??!!? from dealer?

[ebwly Lurker Find all posts View Profile Close ebwly]

So I purchased a GXL recently and am currently on a road trip to Brisbane when I went to fill up the tyres cos I was carrying a heavy load and found them to be 57 psi!???!?

Is this even safe? I thought normal tyres are meant to be around 32 psi?! Granted I'd already driven them for 4-5 hours today and the heat would be added 4-5psi but still 52 psi on prado tyres? Is there something wrong when the dealer filled it?

Thanks!

[brogers Advanced Member Find all posts View Profile Close brogers]

Personally, I believe that 34psi for the stock is way too low for highway driving, fine for downtown tokyo etc maybe...
I would run the stock tyres with a stock load at say around 42psi on the highway.

Some folk use the "4psi rule"...typically a correctly inflated tyre (inflated to the right pressure when cold) will increase in pressure with use by about 4psi.
Whilst 54 psi is not dangerously high I believe, and they are clearly hot and with a heavy load have gotten quite hot I would suspect....but it seems high doesn't it?

Its best to check the tyres when cold, and I would try somewhere around 42-44psi maybe even up to 46psi with a load I guess..and see how that goes.
The tyres probably should not need to go over say 50psi I guess. Its been a long time since I ran with stock Grandtrek tyres.

Have a look on the forum elsewhere ebwly, there has been a lot of discussion about tyre pressures elsewhere on the forum. Too low a pressure will increase tyre wear and make handling a little worse, too high tyre pressures will can affect the amount of rubber in contact with the road and also affect handling...but personally, I have found the standard recommended tyre pressures on car placards are often a little on the low side..and I found that to be the case on the Prado as well. 34 is too low, 57 is getting a bit high.....someone with tyre pressure monitoring who know the pressures in real time through out a trip might be able to comment further about how much tyre pressures fluctuate on a trip. I hope that helps somewhat?

[fogs Lurker Find all posts View Profile Close fogs]

Just speculating about the reason but I got a new car a few years ago and the tyres were over-inflated at delivery. The dealer said that they arrive with over-inflated tyres to reduce flat spots while it's sitting on the boat etc but then should be checked and reduced at pre-delivery. Maybe they just forgot to check the tyre pressures?

[ebwly Lurker Find all posts View Profile Close ebwly]

Hi everyone thanks for the answers I checked later on the tyre wall and the tyres said 51 psi max so I reduced it down to 54 psi (granted this was hot) so I think I should be ok.

The issue is therefore whether (since I'm driving to Fraser Island) i should deflate to 20psi (what everyone says) which is assuming a normal tyre of max 38-40 psi or, given that I am on 51psi for my tyres I should deflate to 30 psi instead but I guess trial and error.

But thats for another thread sorry.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

There are some really good discussions on this forum about tyre pressures and a lot of strong opinions. Ultimately you should have enough pressure to prevent excessive tyre deformation and heat build up from deformation, as it is these two factors that kill tyres. Also on bitumen, deformation due to low pressure stuffs up handling and braking. Easy enough to experience if you go onto a test track and play with pressures. This is where the 4psi rule comes from.

I personally run 40 psi (cold) around town and 46 front / 50 rear when towing on the highway.

All these rules go out the door on sand, where you want to maximise the tyre contact patch by reducing tyre pressure.

[Guest Close Guest]

If the sidewall says 51psi max then you shouldn't exceed this.

Tyre pressure for the different terrain is dependent on the terrain and the sidewall stiffness. And not on a set difference below the max pressure. So on sand, start at 18psi and go lower if you get into trouble.

[sweetpea Senior Member Find all posts View Profile Close sweetpea]

So I purchased a GXL recently and am currently on a road trip to Brisbane when I went to fill up the tyres cos I was carrying a heavy load and found them to be 57 psi!???!?

Is this even safe? I thought normal tyres are meant to be around 32 psi?! Granted I'd already driven them for 4-5 hours today and the heat would be added 4-5psi but still 52 psi on prado tyres? Is there something wrong when the dealer filled it?

Thanks!

Congrats on the new vehicle but I was surprised to see that you had loaded up the vehicle and driven it for 4-5 hours without having checked the tyre pressures.

Each morning on a long trip and after every service I always check oil and water levels, all the wheel nuts, the batteries are still secure and cold tyre pressure including the spare. (I tossed the hard cover because it is just to hard to check the tyre).

I drive an SX 3 door and even loaded up and with the camper (about 1000kg) on the back I don't find I need more than about 25-30 kpa above the placard for the standard Dunlops. 25 kpa is about 5 psi. I run standard suspension and have no bulbar or winch so I am not very heavily loaded even for the longer desert trips.

Someone once accidently put an extra 10 psi in my tyres and it was immediately noticeable because the steering was so light and the suspension was jittery an uncomfortable. I can't imagine what it is like with 54 psi which is over 20 psi more than the manufacturer recommends.

I carry an IR thermometer which lets me quickly walk around each time we stop to check the temp of all the tyres and wheel bearings (especially the trailer bearings) which pretty quickly highlights any coming problems.

I know the vehicle and tyre manufacturers tend to err on the side of comfort but an extra twenty something psi seems a lot too much to me.

S.

PS the maximum pressure on the tyre is just a pressure that must not be exceeded but has no meaning in working out the pressure you should be using.

[cbm8880 Senior Member Find all posts View Profile Close cbm8880]

57psi = 390 kpa

My bet is that they have read the wrong side of the gauge and aimed for 35psi, but instead put in 35x10 kpa (as most dual scale gauges are marked).

Sand is a whole different discussion, but if you haven't driven in sand before you'd be aiming around 15-18psi and maybe down to 13psi if it's really soft. Just drive smoothly, don't take corners at speed and use very little brake if you can.

[Doug32 Member Find all posts View Profile Close Doug32]

When I picked up my 2014/15 GXL it had 30PSI in the stock tyres. The information plate on the door pillar advises that 200Kpa be used (29PSI). I guess this pressure is average for driving around on black top and city speeds without much load.

[Guest Close Guest]

When I picked up my 2014/15 GXL it had 30PSI in the stock tyres. The information plate on the door pillar advises that 200Kpa be used (29PSI). I guess this pressure is average for driving around on black top and city speeds without much load.

It is more biased towards a plush ride - something that dealers want to promote during a test drive.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

The manufacturer recommended tyre pressures are all about quiet and plush ride, and not tyre life and performance.

Interesting experience if you ever get to play with tyre pressures on a skid pan. The most surprising thing for me was that tyres perform better in the wet and aqua plane less when they are inflated to a higher pressure.

[sweetpea Senior Member Find all posts View Profile Close sweetpea]

The manufacturer recommended tyre pressures are all about quiet and plush ride, and not tyre life and performance.

Interesting experience if you ever get to play with tyre pressures on a skid pan. The most surprising thing for me was that tyres perform better in the wet and aqua plane less when they are inflated to a higher pressure.

I've only driven on skid pans in cars and the instruction was always +4psi.

In your experience, what is the best pressure to run (over that on the placard) for best performance in the wet?


Cheers,

S.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

I've only driven on skid pans in cars and the instruction was always +4psi.

In your experience, what is the best pressure to run (over that on the placard) for best performance in the wet?


Cheers,

S.

We didn't over inflate, but ran about 6 psi over placard pressure, this was in a car. The vehicles would start aquaplaning really badly the more you let air out. In the dry braking and sudden evasive manoeuvres also become really difficult the softer the tyre is.

[Limo Guy Junior Member Find all posts View Profile Close Limo Guy]

Before becoming an old fart with a caravan I was involved in 4wd clubs and training in W.A.
In sand I used to get novices to place a stick in the sand 20 mm away from the sidewall and deflate till it touched.
Depending on tyre this related to 18 - 20 psi, I personally removed the valve and when the air escaping started to whistle replace it giving me 18 psi left in tyre.
Takes practice not to lose valve so need cap ready and spare valves but never used a gauge unless I had to go to 10 psi in middle of summer on Calcup Hill.
The sand in this area turns to powder and the hill is long and steep.
Normally I run at 40 and increase rear when under load using 4 psi rule.

[ebwly Lurker Find all posts View Profile Close ebwly]

Yes...we accidentally inflated to 57 (because we thought since we were carrying a heavy load should overinflated a bit).

Bad idea. drove for like 50 ish kms and realised something wasn't right. Deflated to 53. Which still wasn't right. Asked a guy next to us and he had 40 and 42 on rear.

So stuck with that!

Thanks everyone for their tips.