I was told many years ago by an old fella how he suggested I should determine the pressure I needed in my tyres so I thought I'd share the information with you all.

He said put them at the recommended pressure & then take a long drive on a highway 100km/h 60 mile/h that would heat the tyre up, say 30 minute or longer drive. Then recheck the pressure straight after I stopped & the result should be close to 4psi higher than the pressure when the tyres were cold.

According the the old fella if the pressure was higher than 4psi difference, then the original pressure was not correct & the tyre is either under or over inflated causing the tyre to heat up more than normal, this will cause the pressure to increase with more than 4psi difference & the extra pressure would cause abnormal wear on the tyre

Often I would find that the recommended pressure of the tyres were too high. I have followed this procedure for 30 years & always gotten excellent even wear on all my tyres. Of course this would not be effective in cold climates as that would change the heat build up in the tyres, but where I am here in Australia I don't have the changes from hot to extreme cold climate others have.

This is only effective if the wheel alignment & other mechanical parts are in good working condition as this would also cause the variation in pressure if say the alignment was not correct.

I'm sure others will give their opinion about this not being the right way to set tyre pressures but it has always worked for me & often I have gotten greatly extended life from my tyres.

It is simpler, cheaper and more logical to buy a compressor and tyre gauge, and to follow the instructions to check the tyres when cold.

I agree completely that having a small compressor and a good pressure gauge are an excellent idea. Many car drivers haven't even got the gauge which is a MUST as many petrol stations, the pressure gauge is either missing or broken or inaccurate!!!

Sometimes all three (if that were REALLY possible!!!)

But you will see in a recent post of mine here (post #4, a few hours ago!), that checking the tyres when in use, can be safely and correctly done even without a pressure gauge, just by checking tyre temps while driving! (or better said, during a stop while driving!!!)

This link may bring you there:-

Backhand Method of Tyre checking

This to my mind is the best way as it actually tells you how the tyre is reacting to the load/driving speed AT THAT TIME!!

I cannot say how many years I have used this method, more than thirty at a guess....never ever had a blowout on any tyre that I have had fitted and looked after, bought new with car or whatever.....and I have had really good tyre life as well, above the average for the same car type.

I agree completely that having a small compressor and a good pressure gauge are an excellent idea.

Do you have any hints on how to calibrate a tire pressure gage?

The best way I know is to visit several filling stations. Measure a tyre with your gauge and then measure with the filling station's, compare and note.

After 4 or 5 filling stations, yours should come out in the middle somewhere and the differences should be only a few pounds of pressure, anymore than that, simply ignore the value from that filling station.

You can do this over several weeks noting the differences with a block and pen....

Its obviously not a 100% perfect method, but as the actual pressure used is more a function of tyre temperature, it should be good enough.....even if your needed pressure (temp wise) is say 35 Lbs. on your gauge, but the "real" pressure is in fact 32 Lbs., who cares?

I liked your post, a lot of collected wisdom.

I have a slightly different method, mainly due to the fact that sometimes my car is heavily loaded, sometimes not and sometimes I have a heavy trailer to pull. It allows me to drive safely with little effort.

My method is called the "Backhand" method.

Firstly, I run the car tyres at the correct pressures for maximum load taken from car manual as a basis, all the time! The German police check tyre pressures at a simple document check stop!!!

This makes a slightly harder ride that after a few days will not be noticed anymore. The positive effects are a cool running tyres, better braking performance, slightly improved steering response and extremely long tyre life, far beyond what most drivers achieve. They think I am lying to them sometimes when I tell them how many kilometers I achieve....

Anytime, but especially when loaded, after about 30 minutes of motorway driving, I stop and test the tyre temps using the back of my hand, if the tyres are warmer than I am, then they get some extra air pressure till the temperature stabilizes at my blood temp or slightly less.

If the tyre(s) is/are really cold still, then the pressure is a little too high - even in winter. Reduce pressure slightly and check again.

A normal road tyre running slightly under human blood temperature is at the point of optimal grip.

Too cold and grip is lost, too hot (overloaded for the pressure) and the tyre can explode in usage, maybe causing an accident, not forgetting increased fuel usage and extra wear/shorter life.

I have had two blowouts in my life, one was my father's car (at 110MPH and me only 17 years old, but with a full license) and the other was a rented car (at about 70MPH), neither of which I had (stupidly!) not personally checked. Both were the worst sort of blowout, rear tyres....not funny. Both times I had passengers, who ALL went EXCEEDINGLY quiet till the cars were stopped.....

My experiences have encouraged me to take the best care of all of my tyres.....

I "eyeball" them every time I drive, even slight air loss is instantly noticeable to me, though I cannot recommend this as a way to check pressures for anyone....but checking the distance between the road and the wheel rim gives a fast indication, but if you are not good at such eye measurement, then use a portable pressure gauge that has been checked for accuracy first..

Do remember that parking unevenly, on a hill for example, may "squash" some tyres more than others....making judgement less easy. Also, having the steering hard over may produce similar effects!! Beware!!

Have a great day.

Yesterday I attended a seminar titled Smart road Technologies here in Muscat .It was for 2 hrs duration. None of the panel lists discussed this critical issue. May be they considered it as obsolete technology!!!!!

That tells you instantly that the seminar was basically rubbish, if it was supposed to help us drive better/safer!!!

Though some cars are fitted nowadays, either from manufacturer or after market, with a tyre pressure monitoring system.

As of now, I have not seen one that monitors tyre temperature as well, which is a simple basic safety point that many forget....its not having the "right" pressure according to the car's manual that you need (though this is a good place to start), but having the "right" pressure for the road type, tyre type, speed and load on that tyre........to my mind, only the temperature tells you that in one single measurement!!!

I allow the tyres on my trailer, to run slightly cooler as constantly changing pressures on a long run, through different weather/temperature is not my "thing" so to say, but at each stop, all tyres are swiftly checked with the back of the hand.....

During those days before TPMS, I worked at a "Filling Station"(Check the oil, the radiator, tires, clean the windsheild, and gimme a dollar gas"). Many of the customers had just travelled from a large city about 110 miles away. One day, a new Pontiac pulled in for a fill up and the owner got out and put his hand on each tire to see if they were hot. They were and he asked me to raise the pressure about 4 lbs. Turns out he worked for Southwest Research out of Austin, TX and was doing reasearch on tire safety. He related to me they had actually hit a dog during the filming of the test. (Accidentally of course) They found most blowouts were the result of low air pressure, which allowed more flexing of the rubber causing higher temperatures.

After that, I began noticing tires which checked lower than normal were indeed HOT! Some to the extent that they were uncomfortable to touch without gloves on. Many of the ones which had a leak and ran low on the way to have them repaired actually smelled of hot rubber.

My advice would be to run them closer to the maximum pressure especially if loading the vehicle heavily and traveling long distances. You'll experience better fuel economy and less likelyhood of a delay in your trip because of tire failure.

Because most tires are belted tires now, they generally will not wear the center when inflated somewhat higher than normal, but I can garrantee low pressure will cause excessive wear and heat.

You are basically agreeing 100% with my last two posts!! Great!!!

Andy,
do you think the tyre manufacturers have got it wrong when they say you have to check the pressures:
Michelin<http://www.michelin.co.uk/tyres/learn-share/care-guide/guide-for-tyre-pressure>
Check pressures when the tyres are cold (tyres which have not been used in the last 2 hours or have covered less than 2 miles (3 km) at low speed).
If tyres are hot when they are checked, add 4 to 5 psi (0.3 bar) to the pressure recommended by the vehicle manufacturer. Re-check the pressures when the tyres are cold.

Goodyear<http://www.goodyear.eu/uk_en/tire-advice/tire-maintenance/tire-pressure.jsp>
It is very important to check your tyres' pressure at least once a month with an accurate tire pressure gauge.

Avon<http://www.avon-tyres.co.uk/car/tyre-pressures>
If you're checking the pressures yourself, try to use a digital tyre pressure gauge - they're not expensive but they are more accurate than the gauge on most garage forecourts. It's important to check the pressures when your tyres are cold, so wait for about an hour from when you last drove on them.

Pirelli<http://www.pirelli.com/tyre/ww/en/car/genericPage/all_about_tyres>
For your safety it is important to check your tyres regularly, at least once a month. Look for signs of damage or uneven wear because improper inflation pressures, misalignment, improper balance, or suspension malfunctions can affect the overall performance of your Pirelli tyre and endanger your safety...Check the inflation pressure on 'cold' tyres.

I suggest that the back of your hand is an inadequate instrument for measuring temperature and a totally insufficient device for looking after tyres.

You obviously know little about big business and their C.Y.A. actions, or you would not even bother to ask........

If you want to do it like the big(ger!) boys tell you to, go right ahead, none of us here will stand in your way, right boys?

Many of us here have the knowledge and interest to understand something new (to you that is, not me!), and make good use of it.

You now have a choice.....

So go away, look in a mirror and start an argument with the image you see there, if that is what you are looking for.

Just remember that I have no interest in your inane comments in the slightest....nor in lowering myself to bother to answer them.

Remember, all big boys make their own decisions with the information they get presented to them.

So make yours. Try and stick to it......you will be well served by my information and probably 75% with the B.B. (Big Boys!)

Have a great day in spite of me, but I somehow think that you will be soon back trying to stir up something more, only you know if you can resist that or not!!!

Bis gleich!!!

Na und? Ich spreche auch deutsch, warscheinlich besser als Du. [Yes and? I also speak German, probably better than you]. If the mechanic to whom I entrusted my car servicing did it with the back of his hand, then the front of his hand would shortly be holding his P45 (for the benefit of non-UK readers that's the piece of paper you get when you are sacked).

Come on now . . . I think Andy was suggesting a qualitative method rather than a quantitative method.

Indeed he was. Unfortunately he was also suggesting that the qualitative was actually better than the quantitative. I am not an engineer, but as it happens my ex-profession was anaesthesia. Anaesthetists can tell you more than you expect about both the science of measurement and the physiology of the back of the hand. I can therefore tell you (a) that the back of the hand is a very inaccurate thermometer and (b) that a contact thermometer is not the best way to measure the temperature of a gas in an enclosed container made of rubber.
This is an engineering forum, from which I was hoping to pick up wisdom. I put it to you that it is unwise to guess at what you can easily and cheaply measure.

Before thermometers were invented, Mothers would check the temperatures of children's foreheads, hot water bottles (or what came before them) and many other things for the correct temperature. Maybe your mother too? Who knows?

I would guess that a Mother (and maybe SOME Fathers too!!), could probably check such things down to a few degrees - fever or no fever for example, which would be between 98.4°F (normal) and 100°F (too hot!!).

Certainly well within the needs for a car driver where even a swing of 10°F would not matter much either way in my opinion......... Now 120°F or more would be quite noticeable and indicate some sort of problem (unless it was F1 tyres, which are allows to run FAR hotter (around 300°F), but only for a very short distances).

An elbow would also be used to test bathwater etc..

Its something that filled in the eons till thermometers were generally available for all, rich and poor. Even in my childhood it was in general usage. It is far more accurate than many believe.

But you yourself do not need to believe, or to try it.....you can remain in your set position for as long as you wish.....just always remember, "horses and water"....

Have a great day!!

Before thermometers were invented
I have great news for you, Andy. Thermometers have been invented. Even more exciting news: the tyre pressure gauge has been invented too, and it is so cheap that any vehicle owner can buy one. Why don't you borrow one and try it out?

Your comment was probably intended to be funny, well it is, but probably not in the way you intended, its funny because it is so pathetically juvenile. You missed the point I was making completely (again!)

If that is the only style of comment you can achieve, how sad for you....I am assuming you are at least 16 years old or more.

If under 16 then my apologies for being so hard on an undeveloped brain.

But thanks for the laugh anyway, as getting too serious is always bad!!!

Do have a great day as well!!

Your post generates a question. You say: "the back of the hand is a very inaccurate thermometer." I will grant that, but how about relative or comparative temperatures? Can it detect hotter, which I suspect is the goal here? Then another question: is the palm of the hand better or worse? (I have used this to check hub temperatures to detect bearing problems.) How about the back of the thumb, which I have used on foreheads?

Then a different question. Truckers carry hammers/clubs/anything to knock on the tires. This knocking process can certainly detect flats which may not be visually evident, but how sensitive is it to other problems? (A good question for the ATHS group.)

You remind me of an old British saying:-

" You can lead a horse to water, but he must drink all on his own". We have the same saying in Germany too.....I expect the USA as well......many still do not fully understand it, even today.....

You may not believe it, your prerogative, but I was not alone here with using temperature to get the right conditions for tyres on a vehicle....read post #7....one of the "big boys" was also there.....

By the way, you demonstrate to all concerned your attitude to life/people in general, not a pretty spectacle.....but you are definitely not the only one with an attitude on CR4, so you do have company, but maybe not on this blog today!!

Also, you appear to forget that if the blog does not chime your personal bells in a nice way, you don't need to turn nasty on us all, so just go and look at something else.....just leave us here alone.

Thanks in advance for your understanding.

Thank you, Andy. As one of a scientific persuasion, I check your references. In one of your references (post #7) I find "They found most blowouts were the result of low air pressure, which allowed more flexing of the rubber causing higher temperatures." To me that represents confirmation: measuring the tyre pressure cold will alert you early on to the possibility that the temperature may rise excessively and risk a blowout. There is no need to get the tyre excessively hot first. Indeed, there is no need to measure the temperature at any stage. It seems that not only the manufacturers but also all the other "big boys" are with me on that one.

Few people willingly start a journey with one of more tyres missing say 20% of its air....so you are missing an important part of some if not most failures of tyres due to under inflation, that is loss of air pressure, after the jouney is started, but very, very slowly over maybe an hour or more.

A leak caused by say a nail, that gets thrown out, or pulled out when braking heavily.

This why the "Stop Sticks use by police forces have "Quills" which remain in the tyre to ensue that the air is lost relatively quickly as just holing a modern tyre, may leave it still drivable for some time...as many have found out!!!

Slow failure of a valve, especially one missing the dust cap, is also possible while driving.

These are both real valid reasons to always quickly check tyre temps in some way at each stop....but even that is still not a 100% guarantee....

Thanks phph001 I have never seen the 4psi increase in pressure any where else but obviously if Michelin think it is an appropriate amount after the tyres have warmed up then I must be on the right track.

I agree with you that temperature isn't an accurate assessment of tyre pressure as environment, road conditions & driving style can affect the temperatures. It may be a handy basic way to check if you don't have a pressure gauge & can be a good indicator something is wrong with the tyres, but an accurate pressure gauge is always best to get even, accurate pressures.

I would never accept it if I was paying a service person to check the pressure & they just put their hand on the tyres & said they were the correct pressure. Probably just for peace of mind knowing I have done every thing I can to prevent a failure.

I actually have Michelin tyres on my land cruiser what a coincidence they say 4psi difference. Being into 4Wding I have occasion to vary the pressure in my tyres on a regular basis depending on the terrain I have to traverse. So I always have my compressor permanently mounted in my truck & keep a good digital pressure gauge with it. I regularly check my gauge against other pressure gauges to make sure it is reading correctly & replace it if I feel it's not accurate.

If temperature is the better indicator of tire performance, perhaps tire monitoring systems should measure temperature as well as pressure. Perhaps technology can create a device to actively monitor both and change pressure as needed (hour by hour) on the road.

I also agree that monitoring the temperature while driving would be an excellent way to asses the tyre condition & would be a great warning especially as a tyre is failing, as it's temperature will increase greatly as it started to fail giving a warning long before you noticed the difference in handling.

I had a tyre on the back of my land cruiser Ute (Aussie for tray back utility) that failed on a long drive when I had no load on the back & it was not noticeable in the handling until it was about to self destruct. Luckily I noticed it early enough to prevent an accident but if I had the temp monitored on all tyres while driving I would have known something was wrong & would have check it a lot earlier.

Maybe some 1 should invent an aftermarket unit that can be fitted to older vehicles to monitor tyre temp while driving

I would agree with this if you could show that there are pre-failure conditions which are detected only by a rise in temperature. This is an exercise in logic. We already have remote tyre pressure monitors (standard on my bike and available as an aftermarket accessory for many vehicles). My car has a different system for detecting tyre inequalities, based on the relative rotation rates sensed by the ABS system. I have already found that this can detect pressure losses. Is there such a thing as a tyre damage which results in running hot without any change in pressure?

Perhaps we can fashion one of these temperature probes inside the valve stem.

http://www.senseor.com/images/stories/download/Brochures/SENSeOR_TSAG100_to_TSAG105.pdf

Strangely enough, tyres running with low pressure (how much too low depends upon speed, road type and load, to name but a few parameters), get hot as the rubber is "worked", but eventually overheating produces enough extra pressure to cause the tyre to fail in a drastic way.....

German autobahns are the best place to see (and smell!!) the results. I have waved down several truck drivers over the years (and almost daily I see the results) when a tyre has got "smoking hot". On a calm day you can smell it a mile or so behind the truck....

Luckily for many truck drivers, they often run on "re-moulded" tyres and the first full sign of problems is when the tread is thrown, but the rest of the tyre often stays inflated.

I looked around on the web and found a few links that "linked" under inflation to overheating and eventual failure, I hope this helps further:-

http://www.aa1car.com/library/tirepres.htm

http://www.aa1car.com/library/tirefail.htm

http://www.tire-information-world.com/tire-failure.html

Hypothesis: temperature rises significantly several minutes before a blow out.

In today's economy, consumers are trying to get every last mile out of a tire. Is it possible that drivers are experiencing more, accident causing, blow outs in recent years?

Would the driver head a temperature warning (i.e. blowout pending warning) to avoid an incident?

It's a hypothesis. As a principle of the scientific method we can mention that a hypothesis must be plausible, i.e. not running counter to existing knowledge. How may this rise in temperature develop? The conventional answer is excessive flexion of the tyre wall, which occurs when the tyre is underinflated. This is detectable by a pressure monitor before the temperature rises. If the blowout is caused by a weakness in the tyre wall (kerb damage) the bulge may not necessarily accompanied by a rise in temperature (gas laws). How else may the temperature rise be caused? This hypothesis may be worthy of testing, but it is inappropriate to embark on measures which assume that the hypothesis is proven.

A very good question.

I personally believe that they almost never check the tyres on a run.......

I have seen car tyres so hot that you could not touch them and not get burnt, well over 200°F I would guess (but I did not have the possibility to measure their temperature, that was pure guesswork only) DAMNED HOT!.

Tyres that have ignored all "NO SMOKING" signs and how bad it is for your health.

Neither of the two drivers concerned knew they were nearly having a BIG problem....one had actually asked me if I knew why his engine smelt so bad!!! He was worried it was going to break down!!

GA.

Great post and the idea would not only be good for the average car driver, but really great for big truck rigs who have even more problems with overheating tyres....as I mentioned earlier, it would be great if it could be combined in one of those remote tyre pressure systems fitted to many cars.