Carryfast:
Judehamish:
Why do mobile cranes stop at regular periods to cool the tyres down?Axle and Gross weight ?.IE those things are bleedin heavy.
They also get very poor ventilation due to the wheel/hub design and poor air circulation beneath the vehicle.
Hammy747:
But weāre talking England, it rains every day here!
Itās more an issue of the combination of weight and road surface temperatures than just speed alone.As I said it rarely gets hot enough here for 56 mph to make the slightest difference to tyre integrity regardless of dry or wet.
The cause is the gas inside the tyre forcing its way out of the casing. This is typically because the gas has heated, thereby expanding, by the additional tyre flexing due to being underinflated which generally will be a slow puncture that has developed over the course of the journey. Other sources of heat might be a brake binding though and sunny day/road temperature would also be contributory. Blowouts from overinflation are very rare and you would need to exceed the tyre manufacturerās safe working pressure considerably.
Damage to tyre sidewalls like cuts or bad kerb scrubbing make it easier for the tyre to blowout but unless the tyre blows out when the vehicle is stationary arenāt strictly the cause.
Another muppet trainer.
OAD - donāt forget that damage to the sidewall are contributory factors as the sidewall is not as strong at the point of damage as it should be, therefore less heat has to build up to get through it.
dri-diddly-iver:
My cpc was a pass 100% even though in my opinion I answered the above question wronghe was adamant that it was constant high speed
This is not the first time either with cpc rubbish, Iāve had countless regarding 15 min break before 6 hrs
Surely you would have questioned this and asked him why the answer is as he said? A decent conversation to explain why you think otherwise and discuss each otherās points and you would have either agreed with him or he agreed with you.
I always offer to justify or explain why I say what I say (I.e show the publication the info comes from or explain my reasoning) this way we can discuss it and decide who is right.
The trainers an idiot!
The tyres are designed to run at 56mph indefinatly, because the vehicles they are designed to be used on are also designed to travel at that speed.
As part of that design though they have to be inflated to the correct pressure and to be used within their load limits. Of course they also have to be undamaged.
Underinflation or overloading can cause a tyre to overheat and fail, and the faster you are going in those conditions the more likley it is it fail.
Thats like saying though, if you drain half the coolant out your engine, then drive down the mway at 56 untill it boils over. The cause of the boiling over is driving too fast, which is nonsense of course, its the fact the engine had half the coolant missing.
This is just another example of the expensive farce that is drivers CPC. 
Carryfast:
Hammy747:
So if itās constant high speed, what if the roads wet? Does it not help cool your tyres?Probably not running at 36 t gross at 65 mph + at midday in June and July in Florida.
No problem there either. Canāt imagine what kind of tire will blow up for no reason for simply traveling with 56mph.
Have driven in hotter states with higher then 56mph, never had problems with tires. Once I had flat tire(iron nail) in cold weather in Utah and once blow up tire(side bubble) in Georgia, but it was spring. Never had problem in Arizona, Nevada etc. with 60+mph
To me this instructor was talking rubbish, air pressure/tire inflation is a lot more important then constant motorway speed.
If tyres were bursting because of continuous running at 56 mph surely that would mean theyāre not fit for purpose wouldnāt it 
Iām not sure what the answer is but I donāt see how it can be that.
And another CPC trainer who hasnāt a clue.
Truck tyres are speed rated, look at the numbers/letters on your tyre, not the size, the ones opposite to the size, the first set denote a load index with optional load index for dual tyres, if they are not steering tyres. The set of numbers is followed by a letter, any letter over āGā are certified to run at 56mph all day long for hundreds and hundreds of thousands of miles.
Most modern truck tyres nowadays are rated āMā, that is 81MPH.
Each letter starting at E denotes an increase of 10kph, so E is 70, F is 80, G is 90 etc, but they DO skip āIā, just to complicate things a bit, I guess it looks like the number one.
the trainer is a bloody muppet.
Cheap Chinese imports are designed to blow out after 2000km or exceeding 30 mph for 15 mins. Heard that in an RDC so must be true 
Iām sure thatās true Raymondo 
I had a double (Ching Chong) coin blow out under 30 mph . 
Made the folks at the bus stop opposite jump 
Had a few punctures but cannot remember having a blow out ever, must mean I paid good money for the tyres I bought. Pssst, I needing a couple so any lying around?? I used to enjoy re-cutting them as well.
Some remoulds donāt hold out to well at a constant 60mph on the bulk tipper in the middle of summer above 30 degrees, not that we get that often now.
And I would guess near side steer axle tyre blow outs could be the result of constant bump up the kerbs in lay-bys by some drivers who practice that abuse of tyres.
I think the tyre pressures are the most important factor, causing increased temperatures
I am in Brazil at the moment, and I have noticed that all the trucks have tyre pressure monitors, which is obviously more important here with the high temperatures,
I was in Argentina last week and they all have them there as well
How do you FAIL the DCPC?
If the cause of blowouts was driving at a constant 56mph then lorries would be littering the motorways up and down the country waiting on tyre fitters!
dri-diddly-iver:
What is it? Did cpc course last week and ended up arguing with trainerHe said continuous high speed ie 56 mph. I said under inflated or badly worn tyres.
It was a pass or fail module so I answered continuous high speed which I donāt think is right.
Opinions please.
Tyres build for the Speed a Lorry can do leaglly,plus some extra for safety. Tyreman can tell you for which Speed your Tyres safe.
Blow out is
1.) under inflated
2.) Damaged by riding the Kerb
3.) locking Wheels
4.) driving over any sharp Metal or similar
Toddy2:
I think the tyre pressures are the most important factor, causing increased temperaturesI am in Brazil at the moment, and I have noticed that all the trucks have tyre pressure monitors, which is obviously more important here with the high temperatures,
I was in Argentina last week and they all have them there as well
When we did Middle east our Tyres had 11 Bar,otherwise they blow out with just 9 Bar. They went hot,and bang
Immigrant:
They went hot,and bang
Priceless! 
the maoster:
Your DCPC trainer was an idiot. That is all.
+1.
