mowermech wrote:
You could always use the redneck/jack-pine savage method of finding correct tire pressures:
1. Load the vehicle to the "normal" load usually carried.
2. On a hard, dry, flat surface make some chalk marks across the tire tread.
3. Drive the vehicle for a hundred yards or so.
4. Check the chalk marks for wear:
a. If the marks are gone, the tire is properly inflated for the present load.
b. If the marks are worn away in the center, the tire is over inflated.
c. If the marks are worn away on the edges, the tire is under inflated.
NOTE: This method works for all on-road vehicles, and should be done with the tires cold.
Sandia Man wrote:
ST tires are not to be filled based on weight as you would on passenger and LT tires, they perform best at max psi and that is the way we filled our ST tires for 3 decades of towing fifth wheels and travel trailers. With all the issues online and on forums about ST tires, we NEVER had a blowout across 4 different RVs and roughly 100K mile across the 30 year span. Below excerpt is from Tire Track website.
Special Trailer (ST) Tire Maintenance
Allowing inflation pressure to drop can dangerously overload a trailer tire, resulting in excessive heat buildup and possibly a blowout. And while not always resulting in immediate tire failure, even a short period of operating a significantly under-inflated trailer tire can cause hidden internal structural damage that can result in tire failure. Tire load capacity is reduced while tread/sidewall deflection and heat buildup are increased anytime a tire is operated without enough inflation pressure to carry its load. The chance of failure greatly increases if trailer tires are underinflated or overloaded.
Grit dog wrote:
^Thats TMI for the OP. He found the max psi rating on the tire. That’s good enough for him….
And you are overcomplicating it.
Grit dog wrote:mowermech wrote:
You could always use the redneck/jack-pine savage method of finding correct tire pressures:
1. Load the vehicle to the "normal" load usually carried.
2. On a hard, dry, flat surface make some chalk marks across the tire tread.
3. Drive the vehicle for a hundred yards or so.
4. Check the chalk marks for wear:
a. If the marks are gone, the tire is properly inflated for the present load.
b. If the marks are worn away in the center, the tire is over inflated.
c. If the marks are worn away on the edges, the tire is under inflated.
NOTE: This method works for all on-road vehicles, and should be done with the tires cold.
This is ok to tell if a tire is grossly over or under inflated but literally makes no sense and has no bearing on the OPs question, unless he’s somehow stranded in the middle of Death Valley with an air compressor and no pressure gauge or some other scenario equally as ridiculous.
Grit dog wrote:Do not divide by 4. Most TTs indidual tire weights are not equal. I used to be on a race car pit crew, and we had scales to measure all 4 wheels at once to set up the car. One day I used them On the TT I had then. It was a real eye opener.
Take whatever it weighs (gvw if you don’t know actual) divide it by 4, look up the pressure for that weight on a chart.
Or go max pressure for the tires on it assuming they’re the proper ones for the trailer, if you’re not willing to look it up.
jadatis wrote:THis works well for vehicles with oversized tires. Fot TTs, not so much
A radial tire stays within a large range with total width on the ground.
So if you found the pressure, beginning high, at wich chalk wears even, you have still a small surface-length on the ground.
Then when keep lowering, at a certain pressure, sides chalk begin wearing off.
At the lowest pressure, at wich chalk still wears even, the surface_length is larger, so larger surface on ground so best contact.
But then mayby at higher speed tire overheats.
So for safety of tires, you have to begin high, and stop lowering pressure, when chalk wears even.
