This is the first time I have consistently pulled double deckers so its the first time I had seen any long term operational issues. On Friday we had 4 trailers VORd at cairnryan due to bald tyres. Every one was a pair of tyres on the rear axle which i suspect is due to someone swapping them over the water but that aside, do they wear out the rear axle tyres quicker than centre or front axle tyres? I would of thought any tri-axle trailer would wear the centre axle quicker but one of our mechanics says for some reason the rear axle wears quicker. Can anyone share their experience on this?
Tri axles pivot on the middle axle so wear is or should be minimal there, thats where our front or rear axle tyres go after recut, and they last months on the middle.
Front axle scrubs a fair bit, but generally the rear axle takes the heaviest wear.
All our triaxles (not double deckers) used to wear n/s rear then o/s front tyres first. Middle ones would last longest as the trailer pivits on the middle axle.
You’ve got to remember that trailer axles are not independant like the axles on the tractor units. (Well at least i think this is the case anyway) Tractors have got diffs or else they would want to go strait when you want to turn and wear tyres out very quickly. When you turn corners, the trailer tyres should be turning at different speeds but can’t as they are linked. One side will be scrubbing as you turn hence why they wear out quicker. Plus the wheels are obviously smaller so probably do nearly twice the revolutions of a super single.
depends also if they have locking rear steer
nick2008:
depends also if they have locking rear steer
Fair point that, if its got a rear steer then the first and second axles will usually wear faster, as the pivot point will be between axles 1 and 2 so both scrubbing.
damoq:
When you turn corners, the trailer tyres should be turning at different speeds but can’t as they are linked. One side will be scrubbing as you turn hence why they wear out quicker.
Not so Damoq, trailer wheels (well, standard trailer wheels that is) are independent otherwise you’d be measuring tyre life in days rather than months. Next time you see a trailer with a wheel jacked up try spinning that wheel, as long as the brakes aren’t on it should quite happily turn even with it’s opposite number firmly on the ground.
I would have thought its how high the front of the trailer sits on the fifth wheel alters the way the tyres scrub,if you watch a trailer thats being pulled by a unit with a high fifth wheel or being pulled by a tug the pivot point is the back wheels ,if its being pulled by a unit with a low fifth wheel its the front ,only if the trailer is dead level it will be the middle 
the maoster:
damoq:
When you turn corners, the trailer tyres should be turning at different speeds but can’t as they are linked. One side will be scrubbing as you turn hence why they wear out quicker.Not so Damoq, trailer wheels (well, standard trailer wheels that is) are independent otherwise you’d be measuring tyre life in days rather than months. Next time you see a trailer with a wheel jacked up try spinning that wheel, as long as the brakes aren’t on it should quite happily turn even with it’s opposite number firmly on the ground.
I thought my theory was right cos whenever I am reversing into a tight gate or whatever, the o/s/f tyre seems to turn at a different speed in relation to the others. I thought this was because the n/s of the trailer takes a wider line when turning like this causing the o/s to scrub. Maybe I should have studied harder during physics lessons at school. 
:lol::lol:
seth 70:
I would have thought its how high the front of the trailer sits on the fifth wheel alters the way the tyres scrub,if you watch a trailer thats being pulled by a unit with a high fifth wheel or being pulled by a tug the pivot point is the back wheels ,if its being pulled by a unit with a low fifth wheel its the front ,only if the trailer is dead level it will be the middle
You still on steel trailer springs with no balance between?
Otherwise, for the vast majority of us our normal within a few inches tractors should and do in most cases equal trailer axle weights, quite possible a tug could lift it high enough to reach the limits of air suspension movement.
I doubt anyone would swap them out on a decker. They do wear very quickly on 17.5’s on the rear then front, then middle axle as has been said. 19.5’s are better as they’re not as diddy but you lose a couple of inches on the deck height.
If you weigh out as well as cube out they will get beasted unless the drivers ginger them & cut down on the knifing round.
Worth having an air pressure monitoring system on them or inflater as if the inside ones are under inflated & a driver knifes it they can pop off the rim.
No remoulds either…
damoq:
I thought my theory was right cos whenever I am reversing into a tight gate or whatever, the o/s/f tyre seems to turn at a different speed in relation to the others. I thought this was because the n/s of the trailer takes a wider line when turning like this causing the o/s to scrub. Maybe I should have studied harder during physics lessons at school.
. If it helps, the majority of my school physics lessons were spent trying to look down Kendra Shepards top!
I think what you’re seeing is the tyre being pushed sideways so its rotational speed is reduced by the sideways forces. There, Mr Wright would be proud of me.
I cant believe that 4 drivers missed 2 bald tyres each. We had the same problem 6 months ago before the brand new ones were in service. Found 1 tyre with the edges separated from the centre of the tread. That would not happen in one trip. I am pretty sure they are being swapped over in Belfast so the new tyres come out of our budget instead of theirs
or maybe someone is selling them!
They seem to eat brake shoes compared with a normal tri axle in my experience.
damoq:
You’ve got to remember that trailer axles are not independant like the axles on the tractor units. (Well at least i think this is the case anyway) Tractors have got diffs or else they would want to go strait when you want to turn and wear tyres out very quickly. When you turn corners, the trailer tyres should be turning at different speeds but can’t as they are linked. One side will be scrubbing as you turn hence why they wear out quicker. Plus the wheels are obviously smaller so probably do nearly twice the revolutions of a super single.
I wish I was as mechanically minded as you!
Juddian:
Otherwise, for the vast majority of us our normal within a few inches tractors should and do in most cases equal trailer axle weights, quite possible a tug could lift it high enough to reach the limits of air suspension movement.
With a Schmitz Cargobull fridge, the whole trailer will ride high when on a tug (the air bags are expanded as far as they can go), but the Gray and Adams and SDC stuff rides the same, (so you have to be careful not to smash the tail lift (underslung type) when backing into a parking bay (with a concrete stop block)).
The G&A and SDCs still tend to pivot on the middle axle when they’re on the tugs though.
the maoster:
damoq:
I thought my theory was right cos whenever I am reversing into a tight gate or whatever, the o/s/f tyre seems to turn at a different speed in relation to the others. I thought this was because the n/s of the trailer takes a wider line when turning like this causing the o/s to scrub. Maybe I should have studied harder during physics lessons at school.
I think what you’re seeing is the tyre being pushed sideways so its rotational speed is reduced by the sideways forces. There, Mr Wright would be proud of me.
Thanks maoster. Probably explains what I see. Good job I’m not a mechanic. Heavens only knows what Moose would think of me.
scanny77:
I cant believe that 4 drivers missed 2 bald tyres each. We had the same problem 6 months ago before the brand new ones were in service. Found 1 tyre with the edges separated from the centre of the tread. That would not happen in one trip. I am pretty sure they are being swapped over in Belfast so the new tyres come out of our budget instead of theirsor maybe someone is selling them!
Maybe. The problem is blokes get complacent with new kit & don’t bother checking it as much as old kit unfortunately them diddy tyres might only last x months & then be shagged even though the side wall & the rest of the trailer looks new.
Yes they do.Because they have little wheels the Deckers that I work on get through a set of rears every 40 thousand clicks,mind you the other axle tyres dont last all that much longer.
Not really suprising when they turn at 3 times the speed of a normal 22.5 tyre.
Ours have cats eyes fitted so the pressures are easily checked before they run so its not down to under inflation.They are running at 13 tonne empty which doesnt help either
I know a handful aren’t doing their checks properly and some obviously think the fuel fairies put red in the trailer tank for them but most of them are good lads. I cant believe that 4 didn’t spot bald tyres on Thursday then seemingly a further 3 trailers on Sunday. I get on my hands and knees to check the tyres and i am fairly sure most of the other guys do too. Even then, its a 3mm policy so they still should not be reaching the minimum tread markers