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Thread: Tire Safety

  1. #1
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    Default Tire Safety

    Tires are likely the most critical safety items on our coaches that we have control of. Yet, some don't place enough emphasis on maintaining their tires.

    Overweight or under inflation are the number one causes for premature tire failure. Do you know the wheel position weight of your tires? If you don't you can't really determine what the minimum air pressure for your tires should be. The tires that share an axle should be inflated to the same pressure. The minimum pressure for all tires on a given axle will be set to the weight of the heaviest side of the axle.

    Our tires are speed rated for 75mph and everyone should be driving at less than 75mph. If you exceed 75mph your tires may fail. The failure will likely be due to insufficient pressure for the speed. Here's an interesting article on speed and truck tires (CLICK HERE)

    For those that haven't experienced a rapid air loss in a tire, there's a natural fear of a front tire blowout. This video may put your fears to rest (CLICK HERE for Video).


    Gil and Durlene
    2003 H-3 Hoffman Conversion

  2. #2
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    I have a question for those with tire pressure sensors with temp sensing in on them along with pressure.

    What kind of temp increases and just what is the temp at 70mph when it's 90 + outside?
    1990 Peterbuilt 377
    3406 B Caterpillar
    13 Speed Roadranger
    No Norgrens


    1 day on paper no machines

  3. #3
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    Aug 2009
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    Joe,

    For many years I ran PressurePro's on my Wanderlodge LXi which had eight Michelin 315's. The steer tires typically increased in pressure from 100 psi (cold at ambient) to 110 psi (hot while traveling 65mph down the highway). This equates to a temperature increase of 50 deg F. If ambient was 70 deg my tire warmed up to 120 deg F. If ambient was 90 deg the tire warmed up to 140 deg F. Pressures increased by 10 psi which is what you'd expect; i.e., theory says you should see a 2% pressure increase for every 10 deg increase in temp.

    My Prevost H345 has 365's on the steer and tag, but I'm not running any TPMS, so I have no insight into how the 365's behave. Judging from my IR Thermometer and rest-stop pressure readings they look to run about the same as my LXi's 315's.
    Last edited by travelite; 06-22-2017 at 03:09 PM.

  4. #4
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    Default

    Michelin says a 10-15 psi increase from cold to driving is typical. I've seen closer to 20 psi at the extreme. I bet anyone crossing death valley today, at 130 degrees, will be testing their tires.


    Gil and Durlene
    2003 H-3 Hoffman Conversion

  5. #5
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    Pressure increases r more than that. My pressure pro used to measure 20 25lb increases on really hot days.

    I also noticed how quickly they come down too. As u hit exit ramps if u monitor pressure just prior to pulling Into a rest area they r down by half the amount by the time u get parked and set the brakes.

    I'm curious about what temperatures r on a hot day.

    A heat gun after stopping is not a real good representation of temps rolling down the road either, if they drop as quickly as pressures do.

    Gill IMHO anyone going across death valley during a 130 degree day, unless in an extreme emergency would be just plain dumb. If u need to get across go at night.

    The only time I came across death valley was a trip back from Pendleton to Chicago in a 73 Cuda with a cam and a gear. It was the middle of the night and I just barley got through without overheating.
    Last edited by Joe Camper; 06-22-2017 at 04:38 PM.
    1990 Peterbuilt 377
    3406 B Caterpillar
    13 Speed Roadranger
    No Norgrens


    1 day on paper no machines

  6. #6
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    Oct 2012
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    Smithville
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    After learning about Steer tire blowouts and how serious they can be. I opted to have the Tyron safety system installed on My new steer tires. I had to sacrifice some of My bling upgrades like LED marker lights had to go on the back burner. But they can come later. At least now I have a comfort level should I ever have a incident. I also have the new TPMS pulse to monitor and detect a problem before it occurs. The Tyron's are expensive , But just a drop in the bucket in the whole scope of owning and maintaining one of these elegant beasts !

  7. #7
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    Rocky,

    I broke down and decided to do the 365 upgrade on my steer tires just to increase my margin of safety. I just got the tires yesterday and still need to get the studs changed.

    You said the Tyron rings are expensive. How expensive? They must be heavy duty. Keeping that heavy tire out of the center depression of the wheel can't be easy.

    I went with Truck Systems Technology's TPMS system for trucks instead of the RV system. Their customer service and product are great. They even have internal sensors.

    I hope you never test your Tyron bands. If you do, let us know how it goes.


    Gil and Durlene
    2003 H-3 Hoffman Conversion

  8. #8
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    Default

    Quote Originally Posted by Joe Camper View Post
    Pressure increases r more than that. My pressure pro used to measure 20 25lb increases on really hot days.
    If you really control for all the factors like increases in ambient throughout the day, direct sunlight, inclement weather, and changes in altitude you'll see 10 to 15 psi increases. All of these confounding factors can add to the increase. I used to do my testing at night time on flat ground in the dry. I wanted to isolate the temperature and pressure increase strictly due to the tire warming up. 10 to 15 psi is it, and in my case it was 10 psi increase and a 50 degree F. increase for a warmed up tire

  9. #9
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    Dave if u went up 15 at night on flat ground that's not a good look when u r driving during a hot day in the mountians. I think the increases I saw were up I-65 flat straight road during the heat of the day, and I had a 40 ftr that was not a heavy bus.
    1990 Peterbuilt 377
    3406 B Caterpillar
    13 Speed Roadranger
    No Norgrens


    1 day on paper no machines

  10. #10
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    My bad Joe, I think I misunderstood your question. I thought you were asking what the warm-up temp and pressure increases would be at an ambient of 90 degs with all else remaining the same. But, I think what you're asking is what do folks typically see in pressure and temp increases during their usual trip through various conditions.

    See, I had a Wanderlodge and it earned its name! I spent countless hours fine tuning the ride and handling. You name it; I did it, and tire pressures were very much a part of my experiments. In order get a good understanding of what truly was happening with pressures, so that I could run on the hairy edge of manufacturer's pressure recommendations, I needed to know what the warm-up increases were under controlled conditions. With this understanding I wasn't shy about bleeding air out of hot tires. I knew how much pressures were expected to drop as ambient temps went down and I knew how much they were expected to rise as I crested Eisenhower Pass. I found if I could maintain my hot pressures at 105 psi my Wanderlodge ride was much closer to the bus I thought I bought. After 10 years of this I said, "Get me a Prevost"! LOL!

    BTW, I didn't see 15, I saw 10.
    Last edited by travelite; 06-23-2017 at 11:32 AM.

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