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RE: New and Old Skins
...... In the case of the Michelin LTX AT/2s the OE tires used by Ford for the past 12 years not only were labeled LTX AT/2s they had the identical tread pattern and weight carrying specs as Michelin LTX AT/2s sold aftermarket. In this particular case do you actually think there is something different between a Michelin AT/2 sold aftermarket and a Michelin AT/2 OE tire? I’m finding this hard to believe.
.... ….. in my world something that looks like a duck and quacks like a duck has always been a duck.
The problem here is that it only looks like a duck.
Having spent 5 years calling on Ford Light Truck, I can tell you with confidence that the engineers are always going to at least tweak the tires applied to their vehicles. And that includes the Michelin LTX AT/2. I can also guarantee that they didn't allow the tire to remain the same over 12 years! I've seen them force changes after 2 years!
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CapriRacer
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11/15/23 08:04am |
Tow Vehicles
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RE: New and Old Skins
Just so everyone understands: OE tires - that is the tires that come on a vehicle directly from the assembly plant - are designed by the vehicle manufacturer, not the tire manufacturer. There are a few consequences of that.
An OE tire is significantly different than any other tire - even if the name on the sidewall is the same!
An OE tire might be a one-tire-in-the-line kind of thing!
Since the vehicle manufacturer is designing the tire, their priorities are different than the tire manufacturer - and they are different than the end user! Vehicle manufactures are more interested in fuel economy and less interested in wear than the average consumer. As a result you will find that generally OE tires give better fuel economy, but worse wear than the norm.
As far as traction is concerned, the OE tire can be a mixed bag. Sometimes it's OK and sometimes not!
If you want more detail, visit my webpage on the subject:
Barry's Tire Tech: OE Tires
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CapriRacer
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11/14/23 05:54am |
Tow Vehicles
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RE: Toyo tires M122 vs M177
The M122 is a regional/urban tire, while the M177 is a long haul tire.
So unless you only drive short distances, the M177 better suits your needs.
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CapriRacer
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10/10/23 04:57am |
Class A Motorhomes
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RE: TPMS - Tire Pressure Increase
This week on our trip I took a look at tire pressure/temp. In the morning before starting one tire 63psi, 55F. After about 30 minutes of driving and outside temps up to 65F, that tire was at 78psi, and 90F. Other tires basically same pattern. Now the "sunny side" of the trailer had tire temps noticeably hotter, 10F or so. and higher pressure as well likely from heat absorption from the sun hitting the black tire.
Now if outside temps hit 90F, I would expect a slight increase in pressure, most of the pressure increase is due to friction induced heat.
Now, the other unkown is how accurate is the temp reading for a TPMS?? Is it measuring rim temp? air temp? or some combo.
And then factor in how dry the air in the tire is. If it is dry, Boyles law works nice. if there is moisture (water) especially if it condenses, pressure will bump up noticeably once it become a vapor. which is a strong function of temperature.
First, water: Unless you have a pool of water in the tire, you can treat ALL the gases in the tire according to the Ideal Gas Law:
PV=nRT (Note Boyle's Law is about the pressure-volume relationship and does not include temperature as part of the law. Unless the tire is expanding, you shouldn't be using Boyle's Law.)
For practical purposes you will hardly ever see liquid water inside a tire. Not only does water evaporate, but the rubber is permeable to water vapor - and the partial pressure equalizes to the outside air. It takes time for gases to migrate in and out of a tire, so even when it is raining, the amount of water vapor in the tire only SLOWLY rises. Meaning you can neglect the effect water might have on the equation.
The rule of thumb is that tires don't like more than a 10% pressure buildup excluding ambient temperature effects (2% for every 10°F).
Doing the math. the ambient temperature ride from 55°F to 65°F results in a 1.3 psi in a 63 psi tire. So deducting the ambient temperature effect, you have a pressure build up from 63 psi to 77 psi = +22%. Not good.
Best guess is that the temperature sensor is reading the temperature where it is located - not the average temp of the pressurized air, nor the ambient air - but you should check with the TPMS manufacturer to be sure.
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CapriRacer
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09/13/23 08:55am |
Travel Trailers
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RE: TT Wear on one tire..only took few short trips
You've got an alignment problem.
Run a string across both tires at the axle level. Compare both sides.
I'll bet the tire wearing quickly is not parallel to the others. That probably means the axle is bent.
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CapriRacer
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09/08/23 07:06am |
Travel Trailers
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RE: Load range E--ST Tire
Not sure how I put this in Class A motor homes? My first post.
Appreciate all the info. To modify my question (my travel trailer is 6000lbs dry. With added cargo 2000lbs it has max weight 8000lbs) my tires are ST225/75R15 load range E speed rating 75mph. Load 2830lbs single/2470lbs dual.
If I put 70-80 psi in my tires and average 60mph am I good to go 1000 miles?
OK, doing the math:
If 4 tires are 8000#, then 1 tire is 2000#, but if we account for front to rear and side to side variation (12%) we get 2240#. An ST225/75R15 Load Range E has a load carrying capacity of 2830# at 80 psi and at 70 psi, 2620#, so at 70 psi, the reserve capacity is 17%.
That sounds good to me. But here's a way to check it. It's called Pressure Buildup.
Measure the pressure and the ambient temperature right before you start out.
An hour later check the pressures and temp again!
You don't want any more than a 10% buildup excluding ambient temperature effects (2% for every 10°F)
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CapriRacer
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09/01/23 04:14am |
Travel Trailers
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RE: Load range E--ST Tire
Does your RV have a vehicle tire placard - located on the front drivers side lower? What does it say for size and inflation pressure?
How old is the trailer? Still trying to sort this out, but it was common for many travel trailer manufacturers to use too small of a tire.
What brand of tires? What country were they made in?
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CapriRacer
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08/31/23 05:27am |
Travel Trailers
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RE: How to search for tires?
Okay, I watched, most, of the video on balancing tires, and no where does he mention that many, perhaps most, trailer wheels are lug-centric, and almost no one will balance lug-centric wheels. I asked a guy at the tire dealer why they don't balance lug-centric wheels and he said they do. But they balance off the center which he said works fine. But if the wheel is balanced hub-centric, but mounts lug-centric, how is that fine? He just kept saying it's not a problem.
In theory, the wheels are machined using the center hole as center - and that includes the lug holes. So using the center hole is nearly the same as using the lugs for lug centric wheels.
Besides, there is a tolerance for balancing - which is why they have wheel weights in increments. The difference in balancing using incremental wheel weights is imperceptible to the user. And since trailers aren't designed to be ridden in, close enough is good enough!
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CapriRacer
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08/17/23 07:58am |
General RVing Issues
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RE: Balance beads and Borg valve stems
There seems to be problems with them:
Bob is the Oil Guy: Balance bead experiment
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CapriRacer
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08/01/23 05:13am |
Class C Motorhomes
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RE: Tires- LT or ST
As a tire engineer, I find these discussions very interesting. It's hard to sort out the experiences some had recently against someone who remembers the way it used to be long ago.
There was a time where LT tires didn't perform very well - which is why the government tests were changed. What we don't have is reliable information about current tires. This is partially because things have improved to the point where actual failures are fairly rare.
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CapriRacer
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07/07/23 07:06am |
Travel Trailers
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RE: Tires- LT or ST
The fact is that the govt. LT tire testing standards are much more demanding than for ST tires. That being a FACT, it is not hard to understand why STs fail so often.
On another note: LT tire choices in the 16" rim size are many. In fact most if not all manufacturers offer Good, Better, Best models to choose from. Such selection just isn't availible in ST tires. There is a choice of ONE from each manufacturer...So if one wishes to buy a premium ST tire,,,There are none availible....But as an observation of the testing standards, the cheapest LT tire is tested to higher standards than any ST tire.
didn't we have a thread a while ago where we found that the testing standard for both tires is virtually the same, but the LT does one test to a higher speed (partially loaded I believe it was at 60PSI) where the ST does a higher max load test? doesn't sound like it is much more demanding, or a fact.
This is the part you missed:But now the endurance testing diverges significantly.
The ST tire is tested at this pressure, time and load profile at 50 mph. After that, the ST test is over.
The LT tire is tested at this pressure, time and load profile at 75 mph. This is a 50% increase over the ST and will induce significant additional load and heating on the tire during testing. After that, the LT test is not complete. Next a “Low Inflation Pressure Performance” test is performed for the LT tire only. The tire pressure is decreased to 46 psi and the tire is immediately run for an additional 2 hours at 75 mph and 100% of rated load.
Thus, the LT tire endurance test is drastically more intense than the ST endurance test.
And here is the part you missed: ST tires are rated for about 20% more load than LT tires. The net effect is the tires are tested at the same load - more or less.
So when installed on a trailer, the load is the same regardless of which type of tire you put on.
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CapriRacer
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06/29/23 05:36am |
Travel Trailers
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RE: trailer tires
Look for tires with a cap ply (or more than one!) Cap plies will be in the tire description on the sidewall - as in Tread: 2 plies Polyester, 2 steel and 2 nylon. The nylon = cap plies. Sometimes it is called polyamide.
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CapriRacer
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06/25/23 06:25am |
Travel Trailers
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RE: Sailun 637
I've been thinking about changing to a heavier duty tire and I'm considering the Sailun's. My problem is I'm not sure if the wheels on my Pinnacle have the capacity for heavier duty trailer tires. It came with 255/85/r16 Goodyear Endurance. Neither Jayco or Tredit Tire and Wheel, their supplier, could tell me exactly what I have. The wheels are 8 lug and the outside width appears to be about 8 inches. Sailun says their 235/85/r16 S637 needs a rim width of 6.5 inches. Other brands give an acceptable range of rim widths but not Sailun. I would hate to order a set and find they wouldn't work with my wheels. No information is stamped on the outside of the wheels.
Tire engineer here.
Wheels: The best information I have been able to gather is that not only does the government not require a max pressure to be written on wheels, but that wheel manufacturers only consider the max load to be important. I take that to mean that stresses in wheel due to pressure are much smaller than stresses due to the load. As confirmation, I note that when people purpose try to fail a tire by inflating it, the wheel isn't what fails.
Allowable rim width range: It's size dependent, not dependent on the manufacturer (brand). That's because there are tire standardizing organizations and they are the ones who set the range - with the agreement of the tire manufacturers. If you see a spec for one brand, it will be the same if another brand doesn't state otherwise.
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CapriRacer
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06/16/23 05:50am |
Fifth-Wheels
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