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Topic: Truck tires driving over 75 mph (Read 1322 times) previous topic - next topic

Re: Truck tires driving over 75 mph

Reply #1 –
Yes, even with proper pressures, road gators are just waiting and a good percentage of RV drivers will have the same result as the famous interstate blowout on YouTube in case of an emergency at that speed. Especially if they've had "one or two on the road."

Our fire department, most trucking/bus companies fill to max cold pressure as stated on the tire and so do I. Good handling, stopping, fuel economy and not much difference in the ride. 65 mph is a good speed to see the countryside go by. And yes, I drive with one hand or arm over the wheel.

Pierce

Re: Truck tires driving over 75 mph

Reply #2 –
Something to consider:  1)  Should you ever get a blowout in the front, it will be loud and sound like a piece of your suspension broke. If you hit the brake, this will accentuate the forces pushing you to that side and cause you to have no steering ability as the tire has lost  traction similar to skidding a tire which would also cause you to be unable to correct direction thru steering.  You need to slowly, slow down and stop.  If anything giving it a little fuel will help you regain steering.  Again, at the point of blowout, forces will force you sideways, possibly causing an inability to steer, as the tire will be skidding sideways.  Also your brain will sometimes just react, and hit the brake, making the situation worse, giving the rv a little fuel might give you a little help in reestablishing an ability to control direction.  I am not trying to scare you, only pass on my education in this area from both classroom and experience.

2) Years ago many service centers, tire dealers, and rv manufacturers started recommending putting the maximum cold pressure that is on the side of the tire for maximum carrying capacity.  Primarily this was to help with lawsuits and also give users some cushion of safety regarding a blowout from overloading and under inflation.  I always do this for the duals on the rear.  On the front I weigh the front axle loaded, use the mfgs inflation chart, and add 10%.  If I am unsure if I have added weight to the front axle (fuel, load, etc.) I immediately go to max pressure from the sidewall, until I can re weigh the front axle.  The rv will ride and steer better with the correct front load inflation for weght on the front tires, I just sometimes go for the increased inflation for safety reasons until I can re weigh each wheel.

3) Do not fool yourself into thinking your too old of tires are safe since they show no weather cracks in the tread or sidewall.  If old the rubber has gotten dry and hard.  That makes for an easier ply separation.  This separation will cause flapping that creates heat, posibly heating the tire above a couple hundred lbs and then, ....boom, you are trying to correct the steering as above.  You need to read what is old and will work for your budget.  I use a maximum of seven years from mfg date, some use six, others use more.  Nothing is absolute. 

4) A blowout can easily cost you 6-10 thousand in damages to your rv, and possibly your life.  Tires can more than just get you stuck somewhere, and cause you an inconvenience, take the time to get educated and budget for this needed expenditure.

Re: Truck tires driving over 75 mph

Reply #3 –
Here's the problem I'm dealing with.  The left pair of columns show pressure vs temp on one of my front tires, the right on the rear.  Since my weight calls for 115psi in front I added 5, making 120 (the sidewall max) my target for cold.  As you see, cold is 120psi at 55 degrees.  Sometimes cold in the early morning is 70 degrees, and it will look overinflated,  sometimes cold at night will be 30 degrees, and pressure will drop below 115.Similarly, my weight calls for 85psi in the rear, but I bump it up to 100, well below the 120 sidewall maximum.  I see no need for 120 in the rears, but might lower my cold pressures to 90-95 if it results in a smoother ride.

All measurements were from PressurePro Pulse LX TPMS system.  I believe some of the temperatures are a tad off as the TPMS sensors are on the ends of the valve stems rather than inside the tire.

52   119            52   99
55   120            57   100
60   121            60   101
62   122            62   100
62   121            65   101
62   121            65   100
70   126            67   103
72   124            72   105
80   130            80   109
82   133            82   111
90   132            85   114
110   139            100   117

Re: Truck tires driving over 75 mph

Reply #4 –
 Some of us are so light on the nose that the H rated tires  request 70- 75 PSI.  I will try to sell my new 5000 mile 295 H LR
 front tires and go back to the  1 in smaller  9R 22.5 ,  25# lighter G rated tires and operate closer to the center of the weight chart. mid 80s or so  . My ORED is 8K# nose and 16 rear.  I run the rears at 82ish. 
    The 295s  drive  fine but it was much  better on smaller tires.    I think the combination of  soft pressure and  narrow rim allows to much lateral wobble.  It was un driveable @ 85PSI. 

Re: Truck tires driving over 75 mph

Reply #5 –
If you blow a steer tire, correct operator reaction is to immediately go to WOT.  Once steering is stabilized, ease off the accelerator and coast to a stop.
Set the tire pressure at morning temperatures.  If mid-day temps are high, tires temps can easily rise to 140-150psi.  That's normal.  Just don't choose that time to drive at excess speed.  If your steer tires are lightly loaded, don't de-rate your tires-rebalance your load.

Re: Truck tires driving over 75 mph

Reply #6 –
Quote from: amos.harrison –
If you blow a steer tire, correct operator reaction is to immediately go to WOT.  Once steering is stabilized, ease off the accelerator and coast to a stop.
I see this all the time on line but not buying the WOT. I've had a steer tire blow on the freeway at about 65. Unless you have lightning reactions, the first thing you do is to correct the steering to keep the coach from diving off the road. In the YouTube video, count the time it took from the blowout to the time he was off the road. For many RV drivers, it happens so fast that they get way behind what's going on and make corrections too late. All the videos that show what do do assume the driver is just waiting for a blowout when in the real world, the driver is probably day dreaming about dinner or checking the GPS.

Imagine if you are making a turn to the right and with the left front tire loaded and it blows. WOT can mean a visit by the forensic team. Or, how about downhill? Imagine a downhill grade with the Jake or retarder on when the blowout occurs. An even worse probable scenario by going to WOT.

In emergencies, people just don't react that fast, plus age and substance consumption also slow things down, way down. Not driving too fast is the best way to avoid the type of accident below. When it happened to me, I corrected as it moved a couple/three feet to the left, backed off the throttle, checked the mirror, pulled across the right lane and got it stopped pretty quickly.

Check the time from blowout to off the road in this video and imagine what you would do. And this is a straight line blowout, not on a curve or downgrade. The blowout happens at very late 26 seconds, early 27 seconds. At 28 seconds, it's way too late to do much of anything except to attempt to correct. He almost did that but...

Pierce

https://www.youtube.com/watch?v=9LkLeljt4t0

Re: Truck tires driving over 75 mph

Reply #7 –
Pierce,

You might choose to watch the Michelin Tire video showing their research and reasoning on why WOT is needed to help with steering control.  One can always continue to steer while nailing the throttle.  It is force vectors in action, see the video.

But as DaveM always said, do what makes you happy.

Re: Truck tires driving over 75 mph

Reply #8 –
Quote from: Rudy –
Pierce,

You might choose to watch the Michelin Tire video showing their research and reasoning on why WOT is needed to help with steering control.  One can always continue to steer while nailing the throttle.  It is force vectors in action, see the video.

But as DaveM always said, do what makes you happy.
I've reviewed the video several times. Again, people don't react that fast and the videos always assume nice straight road. These videos may give the impression you can control your destiny by following the example but in the real world, driving your age, watching you speed are a bit part of surviving.

I was an emergency vehicle instructor for years and spent a lot of time at code 3 speeds, plus a West Coast NASCAR and PRA driver so I'm pretty well acquainted with what people in certain situations are capable of and what they are not. All the training in the world wouldn't help this guy at his speed. Thinking that you could in this situation is dreaming.

Pierce

Re: Truck tires driving over 75 mph

Reply #10 –
I use Steer Safe stabilizer.

Was on my vogue hen I bought it. Thought is was a good idea.

While @ Q 1st year they were @ the RV tent show. I had them install it on the Villa.

Took about 1.5 hours in the desert

They are in Deming NM

Re: Truck tires driving over 75 mph

Reply #11 –
Steer Safe might be on my short list of safety enhancements, but perhaps not necessary.

I was waiting because I didn't want to apply a bandaid to steering play. But that is fixed now with new ball ends on the drag link. My mechanic says everything is tight now.

And going from zero to 1/8" toe in also made a world of difference. Oddly, the steering even feels lighter now. Dunno why.

Anyway, my short list is shorter since the tires were replaced a year ago and will be replaced again at five years. And I have a new PressurePro TPNS system that gives both pressure and temperature on RV and toad tires. I religiously check cold pressure every morning.

And one more thing, I keep my speed down around 60 +/- a few mph. Too much of my driving is in California with a 55 towing limit. Most trucks keep it under 65. Must be lax enforcement. In my trip last summer, where truck and towing limits were often 60mph, the trucks were doing exactly 60. I took that as a sign that a few mph over might not be a good idea. Anyway, after 11 weeks of 60mph or less (think the 101 down the west coast, much less than 60), I'm now quite content at 60 most everywhere.

Re: Truck tires driving over 75 mph

Reply #12 –
Quote from: Tom Lang –
And going from zero to 1/8" toe in also made a world of difference. Oddly, the steering even feels lighter now. Dunno why.

And one more thing, I keep my speed down around 60 +/- a few mph. Too much of my driving is in California with a 55 towing limit. Most trucks keep it under 65. Must be lax enforcement. In my trip last summer, where truck and towing limits were often 60mph, the trucks were doing exactly 60. I took that as a sign that a few mph over might not be a good idea. Anyway, after 11 weeks of 60mph or less (think the 101 down the west coast, much less than 60), I'm now quite content at 60 most everywhere.
Tom,

Yes, 1/8" toe in makes a world of difference. What do you notice the most? All road conditions, uneven pavement, smooth?

60+ gives you time to respond to emergencies. Good point.

Pierce

Re: Truck tires driving over 75 mph

Reply #13 –
I don't think the driver in the video did anything.  No brake lights no obvious correction, maybe just froze.  Have driven and tested lots of vehicles, to see just how they handled at thier limits, from semis, draw-bar trailers and emergency vehicles to minis in competition.  Most fun were double-deck buses on the skid pan.  Up on two wheels is a trip.  So what's my point?  Think it through a lot before it happens to you.  You need to act instinctively.  No time to work it out at the time.  I like the "tread on the gas" mode.  In all the testing I have done the last thing you need when maneuvering is the brake.  Do you really want to change the vehicles dynamics into ANOTHER state while you are already in full "Oh! S**t!" mode?  Also unless you are a very experienced driver with great reactions you should not be driving at the kind of speeds shown in the video.  Remember the formula ego  > actuality.

Also hold on to the wheel that's what it's for.

Keith

Re: Truck tires driving over 75 mph

Reply #14 –
Natural instinct is to hit the brake..................tough to overcome.