Tyre pressures when towing

Just fitted some 265/75/R16 Cooper STT's and am about to regularly begin towing a 2 1/2 ton piece of plant machinery from site to site on a 16 foot triple axle trailer.

Can anyone suggest the correct front and back tyre pressures please? Upon fitting the Cooper STT's, the fitted filled all tyres to 30PSI, but I have a feeling this is incorrect.

Well Steve - I am amazed the guys haven't leapt on the opportunity for a tyre pressure thread - very courageous of you

Normal advice is to up the tyre pressure to the 'max load' rating when towing

To be honest I wouldn't go mad! They're are plenty on here who tow regularly who will know more than me

The reason your trailer has three axles is to carry the load. Too much nose weight can be just as bad as too little. Actual nose weight is not as much as you would think if your set up is correct. That is why you have an adjustable tow hitch so as to get the height correct. I regularly tow a double horse box, complete with two dobbins, or a 3.5 ton trailer full of fire wood with my 90 and I leave the tyre pressures at what the book says. Never had a problem in more than 35 years of towing.

Station House said:

Well Steve - I am amazed the guys haven't leapt on the opportunity for a tyre pressure thread - very courageous of you

Normal advice is to up the tyre pressure to the 'max load' rating when towing

To be honest I wouldn't go mad! They're are plenty on here who tow regularly who will know more than me

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Ah, I didn't know this was a 'popcorn' topic similar to a 'which tyres' topic. Live and learn, hey.

Shifty1962 said:

The reason your trailer has three axles is to carry the load. Too much nose weight can be just as bad as too little. Actual nose weight is not as much as you would think if your set up is correct. That is why you have an adjustable tow hitch so as to get the height correct. I regularly tow a double horse box, complete with two dobbins, or a 3.5 ton trailer full of fire wood with my 90 and I leave the tyre pressures at what the book says. Never had a problem in more than 35 years of towing.

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Currently, all tyres are 30psi. But I looked at the 110 handbook which recommends 28psi front (seems fine) and 48psi rear (worrying).

GreenLove said:

Ah, I didn't know this was a 'popcorn' topic similar to a 'which tyres' topic. Live and learn, hey.

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Oh yes - search 'chalk test' and prepare to be enlightened

By the way, did you get those speakers fitted?

I tow regularly a horse trailer up to 2.5 tonnes and always leave my tyre pressures as per the book. No problem.

Silverlandy said:

I tow regularly a horse trailer up to 2.5 tonnes and always leave my tyre pressures as per the book. No problem.

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Thinking about it, makes perfect sense if the trailer nose weight is right

Station House said:

Oh yes - search 'chalk test' and prepare to be enlightened

By the way, did you get those speakers fitted?

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Yes, and I've been meaning to take some pictures of all the work that's been done recently. Just waiting to install the rear speakers into some custom made storage units. The front speakers work nicely though and produce a decent sound considering what others have reported.

Will update with some new pics soon.

Silverlandy said:

I tow regularly a horse trailer up to 2.5 tonnes and always leave my tyre pressures as per the book. No problem.

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So 28 front, and 48 rear?

GreenLove said:

So 28 front, and 48 rear?

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See second post in this thread

http://www.landyzone.co.uk/lz/f16/defender-110-tyre-pressure-advice-needed-92655.html

Think you'll find 48 at the rear a bit stiff!

GreenLove said:

So 28 front, and 48 rear?

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28 front 38 rear up to 45 rear on max tow capacity. 45 is a bit of a teeth rattler though.

GreenLove said:

Currently, all tyres are 30psi. But I looked at the 110 handbook which recommends 28psi front (seems fine) and 48psi rear (worrying).

Click to expand...

The 48psi rear is for when the motor itself is carrying max load. If your trailer nose weight was anywhere near the max load of the 110 then it would tow like a dog and would probably mean your load was not evenly balanced over the trailer axles.

As a rough guide anything from about 75-100kgs should be a fair nose weight. I've never measured mine so as stated I'm guessing but it works for me. You need some weight bias towards the drawbar to stop the trailer snaking all over the place especially if you tow a single axle trailer. Its not such a problem on multi axle trailers but they carry more weight and when you have handling problems they are normally big ones.

Well, I've just towed 2 1/2 ton back from Ireland on the triple axle on 32 front and 40 rear, and it seemed fine. My gearbox seems like it's on it's way out though - it has trouble getting into first gear and I'm sure I can hear some spinning metal grinding away (the flywheel perhaps?).

All in all though, for the 1st tow with my 1992 110 I'm quite pleased with how she handled everything. She wouldn't get above 50mph, but then that would probably be unsafe when towing 2-3 tons.

Thanks for the advice everyone. You've probably saved me some tread.