JIMNLIN
Oklahoma
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Quote:- ST205/75/R15
- LH-001 (Maybe a Model# ?)
- 8PR 107/102L Load Range D
- Max Load Dual 850kg (1870lbs) at 450KPa (65PSI) COLD
It is a dual axle travel trailer, 6150lbs dry weight.
I'll probably try 65psi.
65 psi is the best idea for a cooler longer lasting tire.
Those minimum pressures for the load charts work best for cars/trucks/suvs with tires at the front and rear corners.
Your tandem axle trailer tires are set close spaced and towards the center of the vehicle. They side scrub on every turn. Higher pressures helps hold the tires carcass and tread belts together as the tire side scrub on turns.
JFY...the "max load dual" indicates the tire capacity when used in a dual position as in dual on a truck (side by side).
Your trailer is a tandem axle and uses the higher 2040 lb tire capacity at the same 65 psi.
check out Tireman9 https://www.rvtiresafety.net/2018/02/tir........inflation-not-same-for-all-trailers.html
As a actual tire engineer he has the knowledge and experience to explain why different tire pressures are used our trucks vs our trailers. Day of reading on tires for our different rv type vehicles.
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ncladfw3
27410
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Sorry, 2 axles with 2 tires on each axle.
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valhalla360
No paticular place.
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ncladfw3 wrote:Sorry, 2 axles with 2 tires on each axle.
No worries. It was a silly question. No one thought you were running duallies on a small trailer.
Also, it's perfectly normal and acceptable for the manufacturer to provide tires that match the axle ratings.
Going with the 65psi from the tire sidewall is probably the best bet based on the size of the trailer. If you are still concerned, you might swing by a CAT scale and get the real weights.
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jadatis
Holland
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Then I made a list with on front of psi 90% of 1 axle, and behind thebpsi for the tandem so 4 tires.
Single load used, because that is usuall on tandem.
Normaly I would substact 6 loadindex steps from ST, because maxload given for 65mph, even if L speedrated given.
But found out this is only for the larger sizes, not done for your size.
And I have a paper list from Michelin, got it from them 10 years ago, when they did not knew I was the mole.
It gives the Agillis 81 R speedrated, 205/70R15 106/104R, so that /75 instead of 70 would explain the 1 loadindexstep higher, and that tire is given maxload for 160kmph/99mph.
I once determined by reactions about screws trembling loose, that 80% using of loadcapacity calculated for the pressure, gives a deflection that wont tremble srews loose.
So 90% used makes weightdifference possible R/L on the axle.
Now you "ONLY" have to determine the axleloads or tandemload 99% acurate,the mist tricky part, and your responcibility, and search back in my made list, and use that pressure.
So dont add reserves or devide by 4 or 2, all done for you.
If you ever weigh per axle-end, I can make a new list for 95% used of 1 tires loadcapacity for the pressure, in wich you then search the heavyest tire back of the tandem. Then hope the others wont go below 80%.
Axleload/cold psi/ Tandemload
1625 lbs/ 25 psi / 3250 lbs
1740 lbs/ 27 psi / 3480 lbs
1855 lbs/ 29 psi / 3710 lbs
1969 lbs/ 31 psi / 3938 lbs
2083 lbs/ 33 psi / 4166 lbs
2197 lbs/ 35 psi / 4394 lbs
2310 lbs/ 37 psi / 4620 lbs
2423 lbs/ 39 psi / 4846 lbs
2535 lbs/ 41 psi / 5071 lbs
2648 lbs/ 43 psi / 5296 lbs
2760 lbs/ 45 psi / 5521 lbs
2872 lbs/ 47 psi / 5744 lbs
2984 lbs/ 49 psi / 5968 lbs
3095 lbs/ 51 psi / 6191 lbs
3206 lbs/ 53 psi / 6413 lbs
3317 lbs/ 55 psi / 6635 lbs
3428 lbs/ 57 psi / 6857 lbs
3539 lbs/ 59 psi / 7078 lbs
3649 lbs/ 61 psi / 7299 lbs
3759 lbs/ 63 psi / 7519 lbs
3870 lbs/ 65 psi / 7740 lbs/ maxloadpressure
3979 lbs/ 67 psi / 7959 lbs
4089 lbs/ 69 psi / 8179 lbs
4199 lbs/ 71 psi / 8398 lbs
4308 lbs/ 73 psi / 8617 lbs
4417 lbs/ 75 psi / 8835 lbs
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jadatis
Holland
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Dry weight then, with 10% (minimum to law) on towbar, would need 45 psi, but you need the weights fully loaded.
1000 lbs lugage is minimum I think, wich brings it already closer to 65 psi.
Sorry for the typing errors, editing in this forum leads to lost post for me.
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Grit dog
Black Diamond, WA
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^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.
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Grit dog
Black Diamond, WA
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jadatis wrote:ncladfw3 wrote:Thanks for the replies. I got some more information off the tires:
- ST205/75/R15
- LH-001 (Maybe a Model# ?)
- 8PR 107/102L Load Range D
- Max Load Dual 850kg (1870lbs) at 450KPa (65PSI) COLD
It is a dual axle travel trailer, 6150lbs dry weight.
I'll probably try 65psi.
Do you mean by dual axle, 1 axle with 4 tire on it(verry unusuall, but they exist) , or tandem axle so 2 axles with each 2 tires on them.
And can you still read the GVWR and GAWR('s)
( Gross Axle/Vehicle Weight Rating)
Lol, what do you think?
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Grit dog
Black Diamond, WA
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Put 65 psi in the tires and let ‘er rip!
* This post was
edited 05/10/23 07:17am by an administrator/moderator *
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mowermech
Billings, MT
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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.
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Sandia Man
Rio Rancho, NM
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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.
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