GL1800Riders Forums banner

1 - 20 of 23 Posts

·
Registered
Joined
·
1,883 Posts
Discussion Starter #1
I read in this forum quite a bit about tire temperature in relation to tire pressure, speed etc. Can anyone tell me what is TOO hot, is it to hot to the touch or what is the best way to determine if your tires ARE running too hot. I just put the palm of my hand on my tire and it feels warm, after prolonged highway riding.
 

·
Registered
Joined
·
1,550 Posts
I've had my rear tire hot enough after a couple fully loaded hours at 80 mph that putting my hand on it was something like one one thousand...two one thousand... three....ouch!

Probably not good but did no noticeable harm.

Since then I've learned from the tire rep that pressure of 41 or 42 is not enough with a load. 45 or 46 is a better bet

Just warm is doing real good. I wouldn't worry about it. You probably have your tire pressure just about right for your style of riding, weight, etc.
 

·
Registered
Joined
·
2,082 Posts
I have a radar temp gun and we have stopped on a day when it was 104 degrees and we were two-up and I mean loaded pulling a trailer and the gun showed about 160 on the rear and 125 on the front tire. I have read that it needs to be over 200 to break anything down. Don't know that for a fact, just figure it would have to get hot enough to melt rubber before it hurt anything.
 

·
Registered
Joined
·
344 Posts
I've seen temps peak at 200 degrees on my Smartire monitor during the heat of summer. The monitor's warning light said the rear tire be cooking back there. The front tire never had the temp spike over 165 degrees (IIRC). At that point we were loaded two-up with trailer and cruising about 75 mph on a miserably hot day. The tire heat was painful to the touch when checking the tire condition. Taking a brief break to check the tires allowed the temp to come down a bit. Back on the road I found that slowing the pace a bit allowed the temp to stay a bit lower. I also found that increasing the tire pressure a couple of pounds allowed the temp to drop 10-20 degrees. Don't ask what pressure it was at because I don't recall. See, the real advantage of the Smartire set up is the realtime monitoring. It's relative to the current conditions, pressures, temperatures, etc. It's less complicated than you might think.

This episode of high temp spike was a reality check that finally allowed me to better understand a couple previous rear tire failures I had encountered over the years. The last failure was a blistered and torn tread near the end of the tire's expected life. I figure that the thinner the worn remaining tread, the greater the high temps will affect it if ridden heavily loaded or agressively. Forgive me if this is common knowledge to everyone else, but it was an enlightening revelation for this boy.

BTW, seeing as I was riding on Dunlops at the time I contacted their tech support for some temp limit info. I could not get any firm temp value other than a simple statement that my 200 degrees is well below temps used during the manufacturing process. So, there is no real need to be concerned about the temperature during routine operation. Given their response to me, I will be less concerned with the high temps when the tire has much rubber still remaining, and a good bit more concerned when nearing the end of the tire life.

Hope my experience here helps someone with their concerns. If in doubt, by all means, contact your tire's manufacturer for their take on the temp issue.
 

·
Registered
Joined
·
19,989 Posts
Tire temperature is not a concern. Tires are designed to run at their speed rating at the recommended tire pressure and load rating without overheating. As long as you don't overload the tires and keep them at the recommended tire pressure I seriously doubt you could come anywhere close to overheating them.

Putting your hand on the tire tells you nothing.
 

·
Registered
Joined
·
2,013 Posts
hello At sturgis the metz guy had NO idea what temp was ok!!(just a salesman I guess) I also talked to the avon guy & he said 160-170 was about it long term (all day on highway) he also stated on the track DOT tires would run 200-220 BUT they only had to last 1 DAY / TRACK SESSION!!!!!!!!. I myself do NOT like 170 rear tire temps..(so I am a panzy) just running down the highway!!!!!!!!!!!1...chuck
 

·
Registered
Joined
·
652 Posts
For the past 18 months I have been assigned to an R&D job where I have been inserting thermo couples into large pads of different types of rubber and then flexing the rubber at a speed equivalent to 150mph. We record the rubber temps every 5 minutes or so. We have tested dozens of rubber compounds and have tested several that closely resemble tire rubber. That's Natural rubber with some SBR mixed in. We are working with guys that work closely with Firestone and Goodyear. What we find is that we experience "blowouts" or reversion, where the rubber actually reverts to a gummy state as it was before curing at a little above 200 degrees. It always fails below 250 degrees. These compounds will reach 200 degrees in less than 15 minutes if they are flexing 10% at a high speed. Less flexing, less heat. Less speed, less heat. What makes your tires heat? External friction with the road is one factor but internal friction is many magnitudes greater. Tires are designed to flex slightly but not very much. The reason tires blow out is more often a factor of being underinflated or overloaded or both than due to tires being worn.

Rubber chemist and enginers have a term called Tan Delta Loss which is a measure of a rubbers internal heat generation vs. flex. No rubber is perfect

Rubber is cured in a press at between 300 to 400 degrees but it is not designed to be operated at that temperature.

Remember that the increase in temperature also increases the internal pressure. The rule of thumb is for every 10° Fahrenheit change in air temperature, your tire's inflation pressure will change by about 1 psi (up with higher temperatures and down with lower). This according to:

http://www.tirerack.com/tires/tiretech/ ... ?techid=73

Some good info there on other tire issues too.

We have tested some very expensive blends that if tire were made from them would cost 10 times what they do now and they can do better but still fail around 350.

If I see 200 degrees inside my tires I would be scared to death. Remember water boils at 212. Water at 140 will scald you. I have never tested the temps on my tires other than with touch. My tires have never been too hot to leave my hand on. If you have a Smart Tire monitor and it has a warning device that is set to a certain warning temperature why would you ignore it? I would check what it is telling me against several tire gauges to insure it is not off. What is the accuracy of the Smart Tire system? The commercial series for trucks is plus or minus 4psi.

I am not against Smart Tire but I view them as a early warning system during a ride not as a substitute for proper gauging. I would like to have it on my bike.

Some links of interest:

http://www.smartire.com/pix/commercial/ ... er_web.pdf
http://www.smartire.com/pdf/productlite ... epaper.pdf
 

·
Registered
Joined
·
19,989 Posts
I won't delete it, but I realized something after reading KZs post that I had forgotten, that most Goldwing owners routinely overload their bikes. Obviously tire temperature becomes a concern when you ride outside those limits.
 

·
Registered
Joined
·
16,862 Posts
With cold inflate to 42 psi my tis generally rise to 46psi after an extended trip and feel warm to touch. Under infaltion builds heat as WV above noted due to flex. I cooked a rear tire last summer by riding it flat -- it blistered my hand almost instantly! No idea of the temp. It got tossed soon after.

prs
 

·
Registered
Joined
·
1,883 Posts
Discussion Starter #10
Thank you all for your replies to my question. I learned quite a bit. After 10 hours of 2 up riding at 75 mph this summer my tires were only " warm " to the touch, so I guess my pressures of 40 psi front and 41 psi rear are in the ballpark.
 

·
Are we there yet?
Joined
·
2,344 Posts
Have any of you ever checked the temperature of the asphalt on a day with temps in the high 90's? I think you will be surprised. It is not uncomon for road temps to get into the 170's or 180's just from the sun shining on it. Fresh laid ashpalt is in the range of 250 to 325 degrees coming out from behind a paver. I have spent many days in my pickup on the job running on this stuff. Part of my job is to keep a check on the road temps for different stages of the laying process. I have checked the tires on my truck several times just out of curiosity and the temps be above 250 degrees and on a day with the ambient temps above 100 I have gotten reading above 280 degrees on my tires. Many times it is parked on this stuff with all that heat just cooking the tires in one spot. I have never had a heat related tire failure in 20 odd years of doing this. Just keep your tires properly inflated and properly loaded and you will be fine
 

·
Registered
Joined
·
652 Posts
Galute,
I don't doubt what you are saying at all. But the devastating heat on a tire will be generated from the inside out. We all know how good an insulator rubber is. I do not think road temperature will have as great of an effect as low pressure. When rubber flexes the outside can still be cool but if you have a way of measuring the inner temperatures inside the rubber you can see what happens. I have some ruptured samples at work that I will try to post some picures of next week. I have seen a rubber sample be 250 degrees 1/4 inch in from the surface while the surface is less than 90 degrees.

So Galute you are right to say that as long as a tire is properly inflated and not exceeding the weight rating they should not be heating. But I do say that a temperature of 200 degress sounds dangerous to me.

I would be interested in hearing from other Smart Tire owners as to what the normal running temps that they see are.

Since the Smart Tire system must be calibrated with a tire guage on intial setup it is only as accurate as the tire gauge used. Am I wrong on that?
 

·
Registered
Joined
·
55 Posts
wv_wingman said:
Galute,
I don't doubt what you are saying at all. But the devastating heat on a tire will be generated from the inside out. We all know how good an insulator rubber is. I do not think road temperature will have as great of an effect as low pressure.
I agree. The tire's temperature at the contact patch is more of a reflection of the road surface temperature than the tire's carcass temperature and the surface temperature is usually very shallow.

The tires inner temperatures can be calculated by comparing the percentage difference between the cold and hot pressure readings. At 80F, a 10 percent pressure change indicates a 54F temperature change, so if the cold pressure is 40 psi at 80F and the hot presure is 48 psi, then the tire's inner temperature is probably around 188F (54*2 + 80). However, if you measure the tire's outside temperature at the sidewall, the reading will probably be around 140F because of the rubber's insulator properties.

The road surface can either heat or cool the tire depending on what is going on in the inner tire. In the winter it is sometimes hard to heat the tire's contact patch enough to maintain adequate traction and the contact patch may cool very quickly as soon as the speeds drop.
 

·
Registered
Joined
·
344 Posts
wv_wingman said:
Galute,
I don't doubt what you are saying at all. But the devastating heat on a tire will be generated from the inside out. We all know how good an insulator rubber is. I do not think road temperature will have as great of an effect as low pressure. When rubber flexes the outside can still be cool but if you have a way of measuring the inner temperatures inside the rubber you can see what happens. I have some ruptured samples at work that I will try to post some picures of next week. I have seen a rubber sample be 250 degrees 1/4 inch in from the surface while the surface is less than 90 degrees.

So Galute you are right to say that as long as a tire is properly inflated and not exceeding the weight rating they should not be heating. But I do say that a temperature of 200 degress sounds dangerous to me.

I would be interested in hearing from other Smart Tire owners as to what the normal running temps that they see are.

Since the Smart Tire system must be calibrated with a tire guage on intial setup it is only as accurate as the tire gauge used. Am I wrong on that?
WV, you're correct in that the Smartire system is initially calibrated using your tire gage. Not all tire gages are created equal but you use the most reliable and consistant gage anyway, don't you? Once calibrated it's all relative from that point on.

If you reread my original post take note of the overall conditions. It's a very hot day, I'm heavily loaded, and going fast down the road. Each of these are very significant contributors to the over-temp and over-stress of the tires. When my Smartire caution light came on it showed the temp high but stable. As I continued down the road monitoring the temp it gradually kept climbing. Safe...maybe not in your eyes but I was actively monitoring the condition for gross change. I ride motorcycles and manage all sorts of other risk as well so this was nothing more than a exceeded limit worthy of continued attention. Recognizing that the limit exceedance is increasing we stopped to remedy the condition.

We kicked back and had an early lunch, allowing the tire temps to come down. Later we slowed the pace and increased the pressure a couple pounds to yield a more comfortable operating temp. Even then we were hovering around 180-185 degrees. That was considerably better given the overall conditions. Now, without a monitoring system, I would have blindly and marrily continued on till eventual tire failure.

Usually, on routine warm summer outings, my tire temps run about 165-175. Heck, this evening they nearly reached 95 degrees by the time I got into work. :lol: It's not summer anymore for some of us. Just an FYI for everyone, the Smartire pressure/temperature sensor is band clamped to the inside of the aluminum wheel and reads the ambient air pressure/temperature without any direct contact to the rubber of the tire. I could just see some of the folks reading WV portion of the thread thinking there are probes stuck into the meat of the tire like a thanksgiving turkey. Rest assured that's not the case.

One more final thought about the rear tires higher temps relative to the front tire. Remember that final drive gear box back there bolted directly to the big aluminum wheel...to which the sensor is strapped onto? The huge mass of aluminum and steel that make up the rear drive train, makes for an excelent source for added heat as well as a poor heat sink to disipate it as well. Just food for thought.

BTW WV_Wingman, great and informative post about your rubber temp testing. :yes1:
 

·
Are we there yet?
Joined
·
2,344 Posts
I agree with you guys about the flex and the heat caused problems. The difference in my application is my tires are not beaten they are just heated to a high temp. If they were to be run low or or otherwise abused at those temps they would deterioate very quickly. I am talking about very slow speeds to parked on very hot ashpalt. The tire gets very hot when sitting on 300 degree material with little airflow. The heat alone does not seem to hurt the tires. Its a combination of the high temps and the beating they are getting that will destroy them. Again, keep em properly inflated and loaded (thus taking away the unnecessary flex) and don't worry about how hot they are, they won't get hot enough to hurt themselves.
 

·
Registered
Joined
·
19,989 Posts
Manufacturers do not publish tire temperature ratings for street tires which explains why tire reps don't know the answer to those questions. They just assign a letter to the tire, at least on car tires. They don't even give that on bike tires.

It is known however, what the optimimum temps are for racing tires, and motorcycle sport radial tires are closer to racing tires than they are for normal street car tires. Ideally, in racing, tire temps should be in the range of 180 to 200 degrees. Below that the tires don't get maximum grip. Above that, you tear up the tires. I don't know how much of that can be equated to motorcycle touring tires, but I'll bet it's not far off. The temps that a bike tire can handle may even be higher because the rubber and carcass are thinner on a racing tire.

Surface temperature does indeed have a big affect on tire temps. Look at what happens on tracks like Talledaga on a hot summer day. They have a hard time not tearing up their tires.
 

·
Registered
Joined
·
2,530 Posts
Just curious as this board tends to blather on about things that are of low if any importance and have minimal, if any, measurable impact on on the ride/longevity/safety of our motorcycles ...

Has anyone every had a heat related tire failure?
(I believe Galute asked, bit noone answered)

How about heat related tire problems with and without new crushwashers?

Are tire temperature higher or lower when using Amsoil?

Are tires hotter when the wobble is present and cooler on the Wings that don't wobble?

Which are hotter? Avon, Metz, Bridgestones or Dunlops?

And....I am shocked :shock: ... that none have brought up one of the better "popcorn" topics.....

Have you measured tire temperatures with and without nitrogen? :lol:

Just havin' fun and bein' a bit cynical.
 

·
Registered
Joined
·
373 Posts
This isn't scientific but at Myrtle Beach there's this bar called Suck, Bang, Blow (named after the strokes of an engine) where you can bring your ride inside (good ventilation). These guys put front tire up against a wall then spin their back tire making smoke and alot of noise. If you pop your back tire the bar will buy you another. Very seldom does a tire go and its always someone who needs a back tire anyway. There's alot of rubber dust laying around the "pit". Long story short, observing this will renew your faith in motorcycle tires because even the old ones in need of replacement just go and go, enduring a phenominal amount of punishment. It's amazing what they'll take.

Scott
 

·
Registered
Joined
·
344 Posts
NJREF said:
Just curious as this board tends to blather on about things that are of low if any importance and have minimal, if any, measurable impact on on the ride/longevity/safety of our motorcycles ...

Has anyone every had a heat related tire failure?

Just havin' fun and bein' a bit cynical.
NJREF, I would rate tire failure on a motorcycle a tad bit higher than crushwasher choice. :wink:

The reason I installed a monitoring system is because I had a heat related failure...twice. In both instances the tire was nearing the end of it's road but still looked in very good condition. More recently... Doing some summer day twisties the rear of the bike felt a bit loose like oversteering. Even the wife remarked something feels funny with a buzz in the frame. When pulling over to check it out I assumed I picked up a nail and was just loosing air. As soon as I looked at the tire I realized it was a serious failure. A portion of the tread was blistering with several blisters torn, exposing the cord of the tire. It looked every bit like the rubber just seperated from the cord like a snake shedding skin.

My fault completely! I did not check the tire pressure before riding that day and I was out having some fun while heading to Branson. Again...entirely my fault! The last right hand twisty was all she was going to take. The blistering and tears were nearly full circumference of the tire, located at the main tread to side wall transition. Just minutes earlier all looked in good condition. Now, with my tire monitor installed, the tire pressure is checked each and every time I ride. The physical condition of the tire is checked at least weekly.

Yes...my name is KZ...and I am a tire abuser. :oops: :twisted:
 
1 - 20 of 23 Posts
Top