Post by: Cristian G on April 19, 2018, 10:16:30 PM
Tug is a 2014 150 Prado, 4 kids to adults and about 100kg of gear, on BF Goodrich All terrains
I’m currently running them at 36 front and 40 rear.
Camper is Ezytrail Lincoln LX, full tanks, gear, food, kids bikes, on 16”ATs. I’ve currently got these at 40.
We are not expecting to go off road on this trip with the camper, so should be sealed roads all the way.
What would you guys recommend?
Thank
Cristian
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Post by: edz on April 19, 2018, 11:26:03 PM
Post by: GBC on April 20, 2018, 04:35:12 AM
Post by: Cristian G on April 20, 2018, 05:44:43 AM
You aren’t saying if the tyres are LT or not which makes a difference. Our MDC trailer has 265-75-16 LT MT Goodrides which I run at 55 lb on the highway - they max out at 80 so they like a lot of pressure. I would probably be adding more air to the rears of the car with a nose heavy trailer as well if they are LT’s. If they are p metrics, 40 psi is about right.Dumar$$e question, what is the LT & P code for?
I just checked and out camper tires are the same as yours, brand and size.
Post by: GBC on April 20, 2018, 05:53:25 AM
Dumar$$e question, what is the LT & P code for?LT = light truck
I just checked and out camper tires are the same as yours, brand and size.
P = passenger
LT tyres have more plys in the sidewall to carry more weight but require much more air pressure to do so.
P tyres come in all terrain (AT) tread patterns too. They are more comfortable, lighter, better on fuel, easier on suspension but not as strong and generally have less tread depth so they don’t get a lot of love from 4wd ers.
The letters and numbers really are important and if people dont ask what tyre construction you have I would suggest their advice isn’t worth a lot. The LT or P or nothing will be on the sidewall next to the tyre size. A load rating is also on the tyre which will also help if you can get that info?
You are asking the right questions not dumb ones
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Post by: Cristian G on April 20, 2018, 05:55:31 AM
Check out the 4 > 6 PSI rule bit on here https://www.coopertires.com.au/media/1400/cooper-drivers-guide-tyre-pressures.pdf (https://www.coopertires.com.au/media/1400/cooper-drivers-guide-tyre-pressures.pdf)Thanks edz.
I don’t know why I didn’t consider that! We do it on the race cars to check setup, so why not on road cars.
Thanks for the link.
Post by: Cristian G on April 20, 2018, 06:02:52 AM
LT = light truckThanks GBC.
P = passenger
A load rating is also on the tyre which will also help if you can get that info?
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I’m used to the load and speed ratings, but hadn’t considered those parts of it.
I just checked the car and it LT as well.
Post by: GBC on April 20, 2018, 06:05:56 AM
Thanks GBC.
I’m used to the load and speed ratings, but hadn’t considered those parts of it.
I just checked the car and it LT as well.
My original numbers stand then. I’d try 45 in the car rears for towing. Enough to be stable in an emergency, not enough to drive you mad. I tend to run a bit more than others though. There isn’t a magic number.
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Post by: Cristian G on April 20, 2018, 06:09:23 AM
I did notice our fuel consumption was more than I expected yesterday, but I put that down to our our high all up weight and the roof pod more than anything else.
Post by: Bird on April 20, 2018, 09:52:05 AM
Quote from: Cristian G
Great, I’ll try that today.judging by how low the arse end is, I'd say its ****in heavy - get used to it :)
I did notice our fuel consumption was more than I expected yesterday, but I put that down to our our high all up weight and the roof pod more than anything else.
Post by: Cristian G on April 20, 2018, 10:24:13 AM
judging by how low the arse end is, I'd say its ****in heavy - get used to it :)The camper is the heavy bit.
I didn’t get to fit helper springs before we left. A victim of poor planning and competing priorities, my prep is well below what I wanted for this trip.
Post by: scott13april on April 20, 2018, 02:01:54 PM
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Post by: OldPaj on April 20, 2018, 05:04:51 PM
Up to 5 Passengers: 29 PSI Front 32 PSI Rear (Highway tyres fitted generally)
Up to Max Load: 35 Front 41 Rear
Trailer Rowing: 38 Front 44 Rear (LT tyres fitted normally)
For the camper trailer (Vista RV Crossover XL) the manufacturer recommends 36PSI (LT tyres) and adjust as necessary at the same time as the car on lesser roads.
Seems to work well, no heat or over/under pressure issues.
Post by: GeoffA on April 20, 2018, 06:57:04 PM
I’d swap to HD rear coils or airbags, not a big job, 2/3 hours perhaps have it done on the trip?
I can swap the rear springs on my Patrol in 30 minutes.....fronts in 45.....
Post by: gronk on April 20, 2018, 07:13:01 PM
I run a couple of psi more than the placard ....35 front ....39 rear....140kgs on the ball.. tyres have never run hot and wear is even across the tread !!
Post by: Fizzie on April 21, 2018, 03:17:43 PM
LT = light truck
P = passenger
The LT or P or nothing will be on the sidewall next to the tyre size. A load rating is also on the tyre which will also help if you can get that info?
Similar question to Cristian.
Tyres on our van are 195/70 R15C, which apparently stand for Cargo, so can I assume that's the same as LT ???
Also have a (I think) load rating of "104 / 102R" - I can see that 104 = 900kg per tyre, while 102 is 850kg - why 2 ratings ??? Interestingly enough, the van's ATM is 1960kg, but, both those ratings, the 2 tyres would only allow us to load to max 1800kg, & possibly only 1700 ???
Post by: edz on April 21, 2018, 08:46:37 PM
From what I understand the two different load ratings on LT tyres, apply to Single tyre use and being used in a dual tyre set up ..
EDIT : Found it .. http://www.tyresizecalculator.com/tyres/tire-speed-rating-and-load-index-for-the-light-truck-tires (http://www.tyresizecalculator.com/tyres/tire-speed-rating-and-load-index-for-the-light-truck-tires)
Post by: GBC on April 22, 2018, 07:49:18 AM
Similar question to Cristian.
Tyres on our van are 195/70 R15C, which apparently stand for Cargo, so can I assume that's the same as LT ???
Also have a (I think) load rating of "104 / 102R" - I can see that 104 = 900kg per tyre, while 102 is 850kg - why 2 ratings ??? Interestingly enough, the van's ATM is 1960kg, but, both those ratings, the 2 tyres would only allow us to load to max 1800kg, & possibly only 1700 ???
Yes, they are delivery van tyres which go fine on trailers assuming you aren’t overloading them. I’ve run them on boat trailers before. Your load rating on a single axle is the 1st one. They are derated slightly on duals because of road camber and bumps meaning they end up not equally loaded. It looks like your tyres might be a bit light on for capacity. They will need to be at max inflation and it may be an offence to use them. What does your compliance plate say?
Post by: Fizzie on April 22, 2018, 11:29:06 AM
Plate gives:
Tare 1600kg
GTM 1800kg
ATM 1960kg
Axle load capacity 1800kg
All of a sudden I'm (quite) a bit worried ??? :-\
Post by: Fizzie on April 22, 2018, 11:58:15 AM
Had only looked at the spare previously as that's easy to read :D, but this time checked the actual tyres as well.
They're actually 106 rating = 950kg each so 1900kg, so, if I'm reading all this correctly, would that make them illegal as they're then over the plated axle capacity ??? :'(
As mentioned, the spare is only 104 rating so I'm guessing it shouldn't be used in conjunction with a 106 on the other side ???
Also noticed that the plate gives cold tyre pressure as only 275kpa = 40psi. First couple of times we used the van & checked the tyre pressures they went from 45 to 51psi then 49 to 54, so we're now running at 52 (forgot to check the hot pressure after our last run :-[) so they're now way over spec's as well ???
This is getting messier & messier all the time :'(
Post by: GBC on April 22, 2018, 06:45:11 PM
Post by: Fizzie on April 23, 2018, 08:03:50 AM
Forget the 4 psi rule, you need to be at the max inflation number written on the sidewall to achieve that load rating.
66psi! :o Bloody hell! :o Isn't pumping the tyres up to that pressure then going to shake the absolute living crap out of the van ???
& if it's so important to run at max pressure (& it obviously is), then why all the discussion re the 4 psi idea, why isn't it just a hard & fast rule - inflate to max rated pressure ???
Quote
I don’t want to cause alarm but it would be worth weighing it in touring trim.
We ran it over a weighbridge on our way out on a trip & came in at 1.8t, so right on the limit, but that was only packed for 4 days so minimal groceries -- wouldn't be good if we were really touring so carrying a fortnight's worth :'( Guess the planned second water tank, battery & solar panel have all just gone out the window :'(
Post by: edz on April 23, 2018, 08:59:28 AM
Post by: GBC on April 24, 2018, 05:18:42 AM
66psi! :o Bloody hell! :o Isn't pumping the tyres up to that pressure then going to shake the absolute living crap out of the van ???I dont see that you have too many other options. Shakng a van to retain control in an emergency doesnt seem like a huge compromise to me. A simple swerve on outclassed sidewalls could end badly.
& if it's so important to run at max pressure (& it obviously is), then why all the discussion re the 4 psi idea, why isn't it just a hard & fast rule - inflate to max rated pressure ???
We ran it over a weighbridge on our way out on a trip & came in at 1.8t, so right on the limit, but that was only packed for 4 days so minimal groceries -- wouldn't be good if we were really touring so carrying a fortnight's worth :'( Guess the planned second water tank, battery & solar panel have all just gone out the window :'(
Post by: edz on April 24, 2018, 06:35:20 AM
Post by: Fizzie on April 24, 2018, 04:31:06 PM
I dont see that you have too many other options. Shakng a van to retain control in an emergency doesnt seem like a huge compromise to me. A simple swerve on outclassed sidewalls could end badly.
Sorry, wasn't disagreeing with you :D Will definitely be putting them up to 66psi for next trip but it still seems an incredible amount ???
As I said before though - where does the 4psi idea come from ??? I don't think anyone has ever complained that their van / CT was too light ;D, & by the many & varied comments here & similar places, most of them are apparently over, or very close to, their legal weight limits, so surely everybody's tyres should be at maximum rated pressure, so why would you want to reduce your pressure or fiddle with it ???
Post by: Fizzie on April 24, 2018, 04:36:50 PM
https://www.youtube.com/watch?v=nd-hUX8memY (https://www.youtube.com/watch?v=nd-hUX8memY) :'( :'(
Thanks Ed, have seen similar but not that particular example.
Really feel for the poor people passing the semi with everything turning pear-shaped instantly - how would you be if you were having a snooze in the back seat at the time them Boom :'(
Post by: Merts on April 24, 2018, 05:29:12 PM
Will definitely be putting them up to 66psi for next trip but it still seems an incredible amount ???
As I said before though - where does the 4psi idea come from ??? I don't think anyone has ever complained that their van / CT was too light ;D, & by the many & varied comments here & similar places, most of them are apparently over, or very close to, their legal weight limits, so surely everybody's tyres should be at maximum rated pressure, so why would you want to reduce your pressure or fiddle with it ???
The 4psi idea works for tyres which aren't at or very close to their weight limit. Basically, a good starting point is to set the pressure at a percentage of the maximum recommended inflation pressure, based on the percentage of the load rating you are loading them too. For example, if the tyre is rated to 900 kg at 60psi, and your wheel load is 600, you could start at 40psi, and use the 4psi rule to adjust up or down to get the optimum pressure.
In your case, as you are pretty close to maximum load, you need to be pretty close to maximum pressure.
As far as rattling the van to bits, it shouldn't be an issue, as the tyre is designed to be at that pressure for that load. The situation where you might have issues is when the tyre is significantly over-inflated when the load is well below the maximum capacity.
Post by: IanS on April 24, 2018, 11:07:32 PM
The 4psi idea works for tyres which aren't at or very close to their weight limit. Basically, a good starting point is to set the pressure at a percentage of the maximum recommended inflation pressure, based on the percentage of the load rating you are loading them too. For example, if the tyre is rated to 900 kg at 60psi, and your wheel load is 600, you could start at 40psi, and use the 4psi rule to adjust up or down to get the optimum pressure.+1
In your case, as you are pretty close to maximum load, you need to be pretty close to maximum pressure.
As far as rattling the van to bits, it shouldn't be an issue, as the tyre is designed to be at that pressure for that load. The situation where you might have issues is when the tyre is significantly over-inflated when the load is well below the maximum capacity.
Don't get too worried about it, as above if your near max load use max inflation pressure, you should also have a manufacturers recommended pressure, what is it?
I would refrain from measuring tyres when they are hot as it doesn't mean a lot, you can get a temp variation from side to side depending on the wind direction and the temperature of the tyre is related to pressure so which side is right?
Fizzie you mentioned earlier about ratings of tyre's, as long as both your axle rating and your tyre rating are greater than your actual load then you are OK, it doesn't matter if you have a 1.6t axle and 1.8t tyres or visa versa, you can carry 1.6t, the lower rated item is always the limiting factor.
Post by: MarkVS on April 25, 2018, 09:00:02 PM
I actually spoke to a technician At BF Goodrich (I am a persistent bugger) and asked him for his advise. He gave me some handy info..
1. This may be obvious, but he said it’s the air in the tyre that carries the load.
2. BFG LT tyres are designed to take 80 psi cold.
3. The less air air you have in a tyre, the more heat it will generate as there is more rubber in contact with the road, and heat is a tyres worst enemy.
4. The idea is to have a tyre maintain its shape on the road, hence the idea is to increase tyre pressure to carry the load and maintain its shape...except for special circumstances like off-road, sand etc. which are then lower speed etc.
5. Car manufacturers recommend tyre pressures that are more to do with the car ( soft ride etc) than the tyre.
So for my setup, on bitumen, over 80km per hour, he suggested 59psi hot on the rears, 50 psi hot on the front. For me, that works out about 50 psi cold on the rear, 44 psi cold on the fronts. He also recommended other pressure for lower speed off-road dirt etc.
It made sense to me. I am trying it out on my current Kimberley trip and so far so good.
Mark VS
Post by: Fizzie on April 26, 2018, 07:54:45 AM
Post by: Cristian G on April 26, 2018, 08:52:57 AM
Great, I’ll try that today.An update on how it worked out.
I did notice our fuel consumption was more than I expected yesterday, but I put that down to our our high all up weight and the roof pod more than anything else.
I changed the pressures to 36 front, 45 rear and 56 in the camper.
The camper was pretty much spot on with warm tyres and got better as water and food got used along the way.
The car was pretty good. Fronts went up about 6 psi , the rears ended up at 55-56 warm. I didn’t bother adding more before getting to Perth, but I think I’ll try starting the rears at 48 for our next outing from Perth in a couple of weeks.
Interestingly, when I upped the pressures the camper became much more stable and didn’t roll or wallow around as much (almost none at all) over bumps or when passing trucks. Before that, it was rolling around like it was loaded tail heavy.
Thanks to all for your help, it made our journey much more pleasurable.
Gorto
Post by: MarkVS on April 26, 2018, 10:11:34 AM
What do you run in the Exodus, Mark ???
same as the rears in the car