Tyre Temperature vs Tyre Damage

Love my TPMS.....saved the caravan brakes when I left them part on!

Give them 10 minutes stopped & then take a reading. That's ABR Sidewinder's advice.

My external sensors are hte same Jack, they go up to about 17c to 24c tops, mostly they are good to see how the suns temp affectes them on that side vs shaeded side, and how that relates to 1 or 2 psi higher in the sun side tyres.

Really, the pressures are the #1 thing for the TPMS for me, saved me a lot of hassle and a few tyres, and that was on the first trip with them to the north Simpson, and recently a drive ADL to MEL where I have a slow leak, it is so good to pick this up early and take whatever remedy you deem fit.

When I run lower pressures, I just slow down appropriately, usually check tyres by hand as soon as I stop somewhere to ensure not too warm.

Not sure how the internal ones are, mabe more accurate for inner air temp, but do they pick up carcass temps in reality ?

One of those little laser temp guns might be worthwhile, have seen them on tracks used by others, very handy to put on tyres, radiators, auto trans, wheel bearings etc.

Sigmund

To have to stop for 10 min to allow heat soak to somewhere isn't any good for anything. A tyre monitor should tyre monitor, not have to stop to allow it to perform.
If that is what has to be done, then the Laser digital infrared unit is the way to go. No waiting. If you want to, you can hang out the window and take a reading while moving.

I have 3 of them and they are useful. You can easily check other peoples tyres as soon as they pull up to compare your rig with it too.

Do it a few times and work out a pressure-temp correlation.

Varies by tyre model.

Just to add an aside, high temperatures lead to high tyre wear. And that is the main issue with tyres getting hot.
Radial tyres run a lot cooler than the old crossplies because they have thinner sidewalls. And 4wd tyres with thin sidewalls get higher mileage. Ever noticed how thin the sidewalls are on some Cooper, BFG and Grandtrek tyres? That is how they get higher mileage on bitumen.

Bantam

Thank you for your comments with which I generally agree.

I will look for the tyre standards manual and have a read.

In my previous web searching it made me curious that Michelin published the temperature vs pressure chart for only one particular tyre. The chart is possibly a generic representation of how high temperatures contribute to tyre damage. However the increments in temperature are minimal at higher temperatures so my guess is that the data was gained during real testing.

Most likely this type of data is obtained by the tyre manufacturers, during testing, of every tyre they make. So my plan was to try and find that data and compare between different tyres.

I have contacted Bridgestone and asked them for the data. The have responded saying I will hear from a technical rep in the near future.

Cheers John

From the link posted below.

Pressure is the prime metric for measuring the performance of a tyre, the consistency and accuracy of pressure to a tyres work capacity is well established. Road race teams as well as mining technicians utilise pressure as an indicator of the work a tyre has experienced. Having personally undertaken hundreds of tyre temperature tests for various manufacturers of OTR tyres I am yet to find any correlation between internal structure temperatures and surface temperatures even though the locations maybe only tens of millimetres apart. Using pressure / temperature devices that bleed air over a sensor, I am yet to find any direct correlation between the bled air temperatures to the critical temperature at the tread/belt interface.


pretty much don't bother worrying about tyre temperature ....... it is a vastly unpredictable result not a cause.

tyre temperature is not the cause, it is the result .... it is the result of things that damage and damage its self

cheers

Bantam

I do not question your statement that temperature is a result of the work being done by a tyre.

Your last sentence of the major paragraph is interesting. Having no experience in the tyre industry I don't challenge what you say. However in my view the temperature that causes the tyre to lose structural integrity must have some relationship to the tyre internal air temperature. It may not be a direct relationship where only one variable exists. However if you take into account a multitude of variables include rubber compounds, load, speed, pressure, tyre construction, road surface etc I submit that there will be a relationship, not direct, but exceedingly complex.

If temperature is a significant contributor to tyre structural integrity, and its effect has a time element, then the "red light" should come on after a period of time when temperatures have been exceeded. All I am trying to do is set a value for the "red line". How long can you go at a certain speed, pressure, load = temperature before you need to change the one or all of the first three ingredients.

I am enjoying the learning experience with this.

Cheers John

"a value for the "red line". How long can you go at a certain speed, pressure, load = temperature before you need to change the one or all of the first three ingredients."

Almost certainly an impossible to plant even an approx red line I feel John, but a worthwhile discussion to get people thinking about those factors.

In reality, on trips there would be minimal opportunity to change load, unless not refuelling fully, or dumping excess water / gear !!
So that leaves adjusting tyre pressures and speed to suit.

Like car fridges and how they perform, there are just too many variables that can affect results.
Things like extreme ambient temp, fierce sun, they heat a bitumen road surface up dramatically and no doubt would make a difference especially if load and tyre pressures were not best adjusted . . . a TPMS would be invaluable to read how tyre pressure may be changing due to heat there in particular.

Then there are factors off road, again with load in particular, at lower pressures, flex of tyres and especially roads with bad corrugations would have a big effect on tyre temps (and shocks !).

I guess the little laser temp sensing guns would be the absolute best thing all round for checking a myriad of temp related items that can have a huge effect on how reliable our vehicles and components are when travelling.

For monitoring tyre temps, a simple check when having a break would enable a factual idea of how they are going, and over time you will develop a gut feel for what the tyres may be needing in certain conditions.

Obviously all this will change if you change tyre brands / models, or on longer trips load close to GVM (or for many over at the start) . . . an ever changing set of parameters.

The laser temp reader, must get one on the list.

The main paragraph in my last post was a quote from someone who tests tyres for a living.

I keep saying it ...,. There is no even close to direct meaningfull relationship between any temperature associated with tyres and the modes of failure.

Read the entire article in the post below.

there are many temperatures in many parts of the tyre and as the author says ... they are pretty much unrelated.

If a particular tyre is being run under pressure there may be a problem with the steel belts working against the rubber ...... the resulting friction may cause damage and delamination ..... common in early designs of steel radial. .... common is some of the old rope that some tyre manufacturers still sell.

There may be localised heating from this, but is may not be reflected in tyre air temperature or even on the surface of the tyre adjacent to the source of heat.

It is a result not a cause ....... if the tyre gets too hot it is too late, the damage is already done

In my opinion tyre temperature monitors are worse than useless ...... it gives people the idea that monitoring tyre temperature is any use at all.

Unless you have a lot of very specific information about a tyre and the temperature effects ........ there can be nothing learned ... not a damn thing.

Hokus pokus, mumbo jumbo and superstition.

WE know very well about load carrying and cold inflation pressure ...... there is some reasonably clear information about pressure reduction and speed reduction.

But any relationships between temperature wherever you try to measure it and any other tyre behaviour defies even tose who do this stuff for a living every day.

cheeers

An important factor to not overlook is that a decrease in tyre pressure reduces the load carrying capacity of the tyre.

"Conventional wisdom" usually sees people reducing tyre pressures when going offroad, but at a time when loads have probably increased, rather than decreased.


Cheers, Baz - The Landy

We keep comming back to load V pressure .... and that is pretty predictable and well understood
even that we talk ONLY about COLD inflation pressures, because the effects of heat are so unpredictable.

once we get outside of the recommended load V minimum cold inflation pressure at highway speeds ....... everything gets less and less predictable and knowable

we need to face up to that

speed reduction at reduced pressure is reasonably well understood, but things are starting to get quite vague

anything to try and bring more certaintly to running at reduced pressure is pretty much futile. there are simply too many unreliable variables.

cheers

..
"there are simply too many unreliable variables"

And this is why this thread has convinced me to get one of these . . .

SAC infrared thermometer

Bunnings infrared thermometer

Or, for the bargain hunter in you . . . EvilBay infrared thermometer

Anytime you are concerned about tyres, or change parameters like pressure or speed, you can just check in a second on a break or whatever.

Of course if you're worried about other things, eg trans temp towing, brake disks / drums under high use, you can do the same with them.

Hey, love multi use tools . . . anyone use these on camp ovens ?

Yes this is well known particularly running retreads.

But this is tyres run very close to their maximum capacity AT recomended pressures and continuously.

this has no predictable relationship with tyres run at reduced pressure and speed.

AND ..... it is not to my knoweledeg measured or quantified.

cheers

Sorry but that article can be little more than pseudo science.

As for adding 3 psi for light truck tyre utterly meaningless

load V pressure is not discussed neither is tyre type ...... Light truck is a very general term.

some types of light truck tyre run lower pressures at load than other types .... fir example there are quite substantial differences between the flotation family of tyres and the common metric light truck tyre ...... tyre profile also changes load V pressure behaviour. ... and every other behaviour.

Some light truck tyres have nearly identical load V pressure profiles and pasenger tyre of the same type and size

So what if you are running a "light truck tyre" close to it's maximum load capacity at 65psi

What if you where running a tyre very low in its load range with pressures in the mid twenties to the low 30's.

note that the graph has no specific temperature on the temperature axis ... so is not of any use at all, not even as a guide. ...it is little more than popular pseudo science.

Now the statement that if a tyre has reached an internal air temperature of 100C damage has occured ....... no doubt ...... but I doubt that the damage is from the internal air temperature ... the damage is from the internal friction in the tyre structure and external influences..... the same friction and external influences that caused the heat.

in a worst case, very low pressures can cause permanent damage to tyres in a matter of meters log before the air temperature in the tyre can change.

internal tyre air temperature is a lagging result ....... the damage is done before the air temperature changes.

Note that speed is not discussed

as for learning that temperatures are at maximum after 30 minutes .... at what ambient temperature, under what load conditions.
it may be that it takes 30 minutes for the temperature to transfer to the air.

Besides even if the graph is anything other than inspired fiction ..... the graph indicates that at low pressures, the tyre may be damaged in under 10 minutes

so ya going to set an alarm at 55C .... how is that going to go in ambient temperatures of 45C and road temperatures much higher than that.?

Note that in discussing tyre pressures, nearly always we reduce the variables by speaking of cold inflation pressure .... because temperature and it's effects is such an unreliable variable

go set your temperature alarm to anything you like ...... but remember is it a lagging factor ..... it shows after the fact.

cheers

And it doesn't even take into account whether the white lettering is inside or outside.
Dave.

Very interesting discussion however the only true way to measure tyre temperature during operation is to take the measurement at the base of the tread rubber where it meets the ply cord fabric. That is how the tyre manufacturers do it, by drilling a series of holes across the tread width (on a new tyre so that the exact tread depth is known) to the exact depth as close to the outermost cord ply as possible but without penetrating the fabric layers for obvious reasons. The tyres are then operated at certain loads and speeds for certain time periods and the temperatures are taken (when the vehicle is stationary) by inserting a temperature measuring probe in to each hole. As already eluded to, the danger temperature is when the tyre approaches the temperature at which they are vulcanised during their manufacture. This is how TMPH (Tonne Mile Per Hour) studies are performed to obtain the basic information necessary for a tyre manufacturer to use the correct rubber compounds to design a tyre for a certain application. So the two critical factors in determining what temperature a correctly inflated tyre will operate at are load and speed. There is an old saying that says you can overload if you reduce your speed and you can over speed if you reduce your load but you cannot do both together and expect your tyres to survive, especially when factors such as extreme road conditions are taken in to account. Obviously passenger and LT tyres are not designed for specific individual operating circumstances but are a compromise of what broad range of conditions can be expected during their normal operation. Their compounds may however vary due to the conditions and expected ambient temperatures in whatever market they are being sold in. i.e. Country to country. Reading the temperature of the air in the tyres is of little value other than for interest sake and is likely to 'worry' the average person rather than provide any valuable information they can do anything about. As has been said, by the time the air temperature is too high??, the damage has already been done. Its a bit like fitting and engine coolant temperature gauge. Most gauges will read normal due to the air temperature in the cooling system, even when as sudden loss of coolant such as a blown bottom radiator hose has occurred. Far better to have a water level gauge or coolant flow meter in addition to the temperature gauge which in itself is a good tool to monitor increases in coolant temperature outside the normal operating range.