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Old 10-18-2012, 03:03 AM   #21
Champ_49
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Ok if we start out with the suggested air pressure what do we do with the pressure gain we get while going down the road. We are now over maximum pressure. I try to figure the weather for the day as to where we start our pressures. But in general we start out with 100lbs and gain about 10 lbs under normal driving conditions. If it gets into the 90's or more as far as outside air temp then I drop it down to 95 lbs. There will always be pressure gains.

Dave
 
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Old 10-18-2012, 03:20 AM   #22
Ozz
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I agree Dave, I started with 100 and early in the trip, they were 106. Then I increased to 110 and checked them after about 30 miles and they were 119, so I backed them off a bit.
NASCAR pit crews have this figured out, first few laps are the warm-up tire laps..
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Old 10-18-2012, 03:30 AM   #23
Gkerlin
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The PSI recommendations are for cold tires at ambient temperatures. The gain in pressure is expected and not a problem. I really think you are over thinking the issue a bit.

Here is a link to the GY RV Tire care guide http://www.goodyearrvtires.com/pdfs/tire-care-guide.pdf

It talks about the issue in there. I see pressures in the 120's sometimes... not a problem

Also - there should be no problem running the tire 10psi or so over what the load calls for. That should not cause a major fast wearing problem in the center of the tread. You need more than that. Good Year themselves say on ST tires that adding 10 psi increases the allowable speed above 65mph. I forget the allowed speed - I think it increased to 70. I can find that pdf if needed.
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Old 10-18-2012, 03:48 AM   #24
Ozz
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For me, if it states 110#, at highway speeds I will set the tires to run them at 110
Over-thinking or under-thinking, I will set the tires at the recommended pressures at highway speeds and heated conditions.
I am a HVAC expert, not a tire expert, so I may be off on this, but what can it hurt to run them at 110.. I have plenty of time to tinker with pressures on the road, and plenty of on-board-air for the tires, if needed.
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Old 10-18-2012, 04:21 AM   #25
Gkerlin
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Ozz I agree with the 110 psi. But that is cold pressure... not warm

What you shouldn't do is take the air out of them when they heat up. If you do you are running the risk of running the tires under inflated. (depends of course how much you are taking out and weight)

the way to check tires is to do them when they have not been driven more than a mile. They should be cold at ambient temps. Those pressures take into account that the tire will heat up and have more pressure when warm.

As you run down the road at speed the tire sidewalls flex each revolution. That generates heat and the tire pressure builds up some, it flexes slightly less with the higher pressure and it reaches an equilibrium for that speed, temp etc.

If you take air out the tire will then flex more, build up more heat etc etc.

I was running my tires at 105 psi. I would usually see pressures around 120 or so. A 15psi increase. If I stopped and dropped the tires back down to 105 when they were hot, I would be in essence running the tires at 90 psi (105 - 15psi).

The cold pressure before you start rolling is what the load/pressure charts are all about.

That link I posted explains this.
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Old 10-18-2012, 04:36 AM   #26
steelpony5555
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I agree, I have always ran my TT tires at the max pressure on the sidewall. We don't have them long enough or drive them far enough to really worry bout wearing the centers out. I haven't wore a trailer tire out yet, and I really hate getting rid of tires with all that tread left lol lol. The way I look at it is if underinflated the tire flexes and really heats up and goes boooom, but if it's even a hair over max inflation going down the road nothing happens the tire is just really hard....
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Old 10-18-2012, 05:26 AM   #27
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I find it interesting on page 20 of the Goodyear link that it states the G614's are only warrantied for 4 years for specific issues like sidewall cracking while other tires are warrantied for longer. For as much as they cost ... it just doesn't figure.
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Old 10-18-2012, 05:35 AM   #28
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Quote:
quote:Originally posted by dieselguy

I find it interesting on page 20 of the Goodyear link that it states the G614's are only warrantied for 4 years for specific issues like sidewall cracking while other tires are warrantied for longer. For as much as they cost ... it just doesn't figure.
Ha... Good catch! I never noticed that.

I guess I could figure out an excuse for the Class A Tires, and the Silent Armor pick up tires...

But the Marabombs have a 6yr vs 4 year for the G614's.

Must be because all of us 5'vrs get those 614's and then load them up until the frame screams!
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Old 10-19-2012, 03:35 AM   #29
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Just set the pressure at 110 pounds cold, cold being in the morning, check them from time to time, again only in the morning, outside temps will change and change your tire setting, stop looking at the tire pressure monitor, let the pressure rise all it wants when driving, you won't hurt them
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Old 10-21-2012, 06:18 AM   #30
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Quote:
quote:Originally posted by RonD

Just set the pressure at 110 pounds cold, cold being in the morning, check them from time to time, again only in the morning, outside temps will change and change your tire setting, stop looking at the tire pressure monitor, let the pressure rise all it wants when driving, you won't hurt them
Agree, never remove air from a hot tire because the TP is too high.
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Old 10-21-2012, 11:00 AM   #31
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It is my opinion after 30 yrs of racing cars and working with tire pressures the outside air temps cause a drastic change in air pressure. So if you say 110 lbs cold (as it says on the tire) that no matter what the outside temp is if it goes up to 120 to 125 lbs that we aren't really at that pressure because if we take air out we are in essence going to be under 110 lbs if we take it down to 110 lbs? That to me makes no sense at all. Pressure is pressure plain and simple. Trust me I have worked with 1/4 lbs increments on a race car and them changes indeed make a lot of difference on the handling of the load the tire does. Some may say its a lot different for a race car and a trailer. I say a tire is a tire, and heat plays a huge factor in both. To check heat by laser you go out on the track with cold tires and make a few laps and then come back in a check temps. If the ambient air temp is lets say in the mid 80's the tire will go out in the mid 80's when you come back in after a few laps it will be in the 170's. and the pressure could increase that short period of time by as much as 10 lbs. What I am trying to get across here is heat and pressures go together and tires all work the same.

The same goes with our trailer tires, the longer we run and the hotter the outside temp is the more pressure we are going to gain along with heat. And heat is one of the worst enemies of tires.

My explanation and I'm sticking to it.........lol

Dave

After reading my post I also should say that if you in fact do take air pressure out because due to excessive heat and travel after they cool off they certainly will be below your start out of 110 LBS. But running with hot tires in with excessive pressure is a road to loosing a tire in my opinion. So after they have cooled off you must air up the tires again. Work yes! But as everyone says here they check there tires every trip and add what they need anyway, so it isn't a huge problem.
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