Tire Temperature

[AJ]

Ever since I got my infrared thermometer I have been measuring my tire temperature, on the steer, drive and tag at, side wall and thread.
My question is;
On a hot summer day driving, say 92 degrees ambient air, black top highway, 60 to 70 MPH, what are the expected normal tire temperatures?

AJ

[Ed Hackenbruch]

Also add in tire pressure to the equation and don't forget that the sunny side will be warmer than the shady side.

[Bob Belter]

Ahoy, AJ,

I've seen my tires --  sunny side --  95f day at 125f -135f, less down-sun.  I'm light @ 33,000# running 90psi main and drive, 80 psi tags.   
At rest stops, I've spotted 18-wheelers with higher and lower temps --   I'd guess loaded or empty.  Some smaller and heavier trailers were above 150f.

Enjoy   /s/   Bob

[JohnEd]

90 degrees ambient.  Surface of the black top is going to be 140....as a guess.  I have been in 140 saunas and all was OK but I can't walk barefoot on seaside blacktop in 90 degree ambient sunshine.  Had to walk on the white stripes at the crosswalk to get to the other side.

Evidently a 140 degree tire is within spec but just what is the spec?  Regardless of the roadway temp I think the mfr must have a top tire temp.  Right?

Camber should give you a temp delta between outside edge and inside and between sides.  What does toe in do to temp on the outside edge?  I know that under inflation increase the tire temp but in the day the tread center of a under inflated tire was cooler than the edges. Same for over loaded.  Race car owners dial in the tire pressure in this manner, or they used to, before they started to monkey around with "push" and "loose" and sway bar tension.  They have been running radials in that arena for 60 years give or take.

This is a great topic.  I have never seen it fully visited here.

John

[Cary and Don]

It seems that on a previous post, it was said that the really important thing was difference in temps between the tires.  We watch that very carefully and have found that a low tire will be hotter than the other tires on the same side.

Don and Cary
GMC4107
Neoplan AN340

[bobofthenorth]

I check my tire temperatures almost every time we stop.  90 to 120 is "normal" but I don't think the absolute temperature means anything.  All I'm looking for is temperature variances which point to tire pressure differences.  Side to side differences of over 20 degrees are common on a sunny day.

[BG6]

Temps will also vary depending on tire composition, construction, tread pattern, vehicle weight distribution, road camber, road material, how smooth the road is, how much wind and where it's coming from, alignment . . .

All you are really looking for is a "flyer," a tire which is radically outside the temp range of the others.

[JohnEd]

What is the max temp a tire can operate at.  Not "in".....but "at".  BOTN reads 90 to 120 all around so hat is the temp at which we should say....gotta slow down OR WTH?

My mind runs to the guy that has the thermo gun and an air compressor at home and uses the same air pressure gauge for all the bus work.   It is reading 25 pounds low and in the winter or at low speed local trips he sees no problem.  One summer day he stops after a 70 MPH run and while stopped he shoots the tires.  230 F but they are all pretty much even....no fliers.  230 or XXX? is where he should panic and say "not even one more mile!".

We are looking for fliers....agreed.   And we are looking for data that is consistent with history.

john

[BG6]

What is the max temp a tire can operate at. 

230 or XXX? is where he should panic and say "not even one more mile!".

You need to talk to the company that made the tires.  That's the bad news.

The good news is that, on big tires, they are likely to have that information to give you.

[JohnEd]

OK!  Bridgestone North America rep said that a temp of 200 degrees, the actual tire casing, could be sustained safely.  He refused to site a temp at which the tire would be unsafe or the max allowable temp.  He mentioned 200 and it wasn't suggested to him so I would think it represents some kind of barrier.  My tire shop owner said that if I saw temps rise to 200 and pressures and load were within limits he would suggest I park till after sundown or back off the 110 MPH speed.  No joke there.


I don't know that that resolves much.  It wa mentioned that some of the low speed, non hi-way, tires intended for local use will self destruct at hi-way speeds in summer temps.  Brand and design and materials must have a serious bearing.  It came up that the "transition region" where the tread belts and the casing plies meet is most often the hottest part of the tire.

John 

[Ed Hackenbruch]

I check my tire temps at stops, but since i have a pressure pro, i can check the tire pressure any time i want by pushing a button. 

[BG6]

I check my tire temps at stops, but since i have a pressure pro, i can check the tire pressure any time i want by pushing a button. 

Useful, but not a protection.  The temp that counts is between the case and the tread, and it can go way up before the pressure will change.

[Ed Hackenbruch]

True, but the temp can go up very quickly in just a matter of a few miles if you start losing air. 

[rv_safetyman]

BG6, your last post just does not make sense to me.  I spent 34 years in the rubber industry, some associated with our tire program and I just can't figure out what your thesis is.

There are a ton of studies about tire failure (most done by credible universities).  They clearly and universally find that low pressure causes the vast majority of tire failures.  I have viewed studies that have the percentage as high as 92%, but none lower than 82%.  

I have seen tires at considerable under-inflated condition with only slightly elevated temperatures.  I have a very strong conviction that tire temperature is not a strong indicator of tire pressure unless the tire is under-inflated by at least 25% and run in that condition for many miles (that condition will indicate significant damage).  It can be an indicator of a damaged spot on a tire ****IF**** you could scan the WHOLE tire.  We used to have a really neat tire test dyno that would do just that (very advanced technology at the  time).  

Your thesis seems to be that somehow the tire generates a temperature that affects pressure.  That is only significant from a cold start to operating temperature and then temperature has a very insignificant impact on pressure.

Like many folks I check my tire AND hub temperatures at each stop.  Once in a while I will not use the temp gun, but rather my hand.  The human hand is a pretty good thermometer up to 140*.  Most humans can lay their hand on something that is 140* and not feel pain that would have you remove it smartly.  Folks who do a lot of welding or work with hot objects can sometimes go to 150*.  Like others, my tire run less than 120* almost all of the time.  I do this inspection as a verification that the tire is not experiencing some type of internal failure that is not related to tire pressure.

Just to repeat myself, tire temperature is a nice piece of information, but not a good indicator of tire pressure problems.  Anyone with a properly functioning tire pressure monitor system ***AND*** whose tires were properly inflated during the installation process (sets the baseline for deflation warning),  should feel very confident that they have the highest probability of not having a catastrophic tire failure.    That assumes that the tire has sufficient ratings for the application and that the installation pressure was based on weight at each tire location.

I hope this is taken not as being argumentative, but rather a strong defense of a very important safety device.

Folks, I have edited this post several times and I still don't think I have properly conveyed my understanding of the subject, but it is time to "let it go"

Jim

[JohnEd]

Jim,

The BG stuff aside, do you think BOTN and I are wasting our time by checking temps at rest and meal stops?

I once fond a wheel bearing going out because the hub was a little warm to the touch and that check will stay with me until someone comes up with a better one.  I know it works.

Thanks,

John