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Mom2twins · 01-10-2021, 02:50 PM

I'm sorry if this has been asked. I see several other posts on tire pressure and am now even more confused with load etc.

I purchased a 2018 Bambi recently and put new tires on it. I didn't specify "tire trailers" though when I ordered them. The PSI guidelines for the trailer say inflate to 65 PSI but the tires themselves day max 50 PSI. Both read tire size ST215/75R14.

I just measured the pressure and they are a little low at 45 PSI. Wondering what I should inflate them too. I'm in N CA where temps area 32 F at night and 50's during the day... Going camping in a few days where it may be a little cooler in the foothills.

Any info appreciated. Again, apologies as I've seen a few posts, but clarification needed for this newbie - Thank you in advance!!

ROBERT CROSS · 01-10-2021, 02:59 PM

16ft Sport...If they are Goodyear Endurance I would stay at 45psi. With the robust sidewalls on the GYE's 45 should be fine.

Bob
🇺🇸
Like these....

McStreamy_ · 01-10-2021, 03:03 PM

I would not inflate above the maximum rating on the tire unless you want to have a bad day. You should be able to do a quick google search for the type of tire you have and find a load chart that will recommend PSI based on how much weight is on the tire. You always want to include some buffer, but you shouldn't inflate beyond the max rating. And that PSI reading is for a "cold" tire before it's been driven for the day. Just my .02

LNBright · 01-10-2021, 03:05 PM

Which size Bambi? What brand of tires?

The amount that the tires are inflated ties to the amount of weight they can bear.

For example, mine has a gross weight of 5000lbs, which would be 2500lbs/tire needed. If I had the Goodyear Endurance on it in a 14" wheel, the max for that tire is 2200lb@65psi, which wouldn't be quite enough: but a 15" Endurance can go to 85psi, and support 2830lbs, which is more than I would need, and thus, I can run at lower psi, perhaps at 65 or 70 instead.

Check the brand of tire you have to see how much weight it can support at its max psi; I hope it's enough for your trailer.

ROBERT CROSS · 01-10-2021, 03:07 PM

Quote:

Originally Posted by McStreamy_

I would not inflate above the maximum rating on the tire unless you want to have a bad day. You should be able to do a quick google search for the type of tire you have and find a load chart that will recommend PSI based on how much weight is on the tire. You always want to include some buffer, but you shouldn't inflate beyond the max rating. And that PSI reading is for a "cold" tire before it's been driven for the day. Just my .02

...a bad day?
Under-inflated is much more of a concern.

Bob
🇺🇸

Mom2twins · 01-10-2021, 04:34 PM

I have Carlisle Radial Trail HD Trailer Tire-ST215/75R14 102M 6-ply

So it looks like the max weight capacity is 1870 - if that is per tire and it's 3740 total then I'm good, if not I probably need to look at getting other tires. Although, these are literally brand new (only 2 short trips on them). I replaced what was on the trailer with like tires but didn't pay attention to load.. ugh.. baby steps.

Mom2twins · 01-10-2021, 04:43 PM

Quote:

Originally Posted by LNBright

Which size Bambi? What brand of tires?

The amount that the tires are inflated ties to the amount of weight they can bear.

For example, mine has a gross weight of 5000lbs, which would be 2500lbs/tire needed. If I had the Goodyear Endurance on it in a 14" wheel, the max for that tire is 2200lb@65psi, which wouldn't be quite enough: but a 15" Endurance can go to 85psi, and support 2830lbs, which is more than I would need, and thus, I can run at lower psi, perhaps at 65 or 70 instead.

Check the brand of tire you have to see how much weight it can support at its max psi; I hope it's enough for your trailer.

The max weight capacity is 1870 on these Carlisle Radial Trailer HD. I wish the garage would have said they weren't right for my trailer. I ordered online.. they came up as an option but the manufactured trailer weight is 3500 lbs. Looks like I need new tires then? I'm supposed to take a short trip about 90 min from this week and not sure it's safe with these tires now though we've made it on 2 other shorter trips fine.

LNBright · 01-10-2021, 05:04 PM

Based on this, the Carlisle is 1200lbs/ tire:
https://www.amazon.com/Carlisle-Radi.../dp/B01IHIMBEY

Your 16’ when empty is 2860lbs, has a gross rating of 3500lbs:
https://www.rvusa.com/rv-guide/2018-...n-16rb-tr34628

So, yeah... your trailer weighs more than those tires are rated for, if those numbers are correct. Looking elsewhere, turned up Carlisle’s page:
https://www.carlisletirestore.com/rad_trl.htm

There, it says the max load is 1870lbs. If that’s actually the case, your empty weight is okay, but you would still be over at your max weight.

My suggestion would be to: inflate to the max psi (50psi), travel light, don’t speed.

I would then also suggest a set of 15” tires with Goodyear Endurance tires to replace these once it’s time.

Good luck...

BayouBiker · 01-10-2021, 06:13 PM

I see that the max load is 1870 as you say. That is a per tire load rating. so 3740 max rating. Now the trailer has a GVWR of 3,500 and you have at least 10% and probably 13-15% on th e tongue. Lets use 13% so the weight on the axle is 3,045 lb. You have 695 lb to spare and that is good because you want a minimum 15% margin and 25% if you exceed 68 mph. You have just under 24% margin so you are in good shape with those tires . Do inflate them to max 50 psi cold. So each time you start off you want to be right near 50 psi and you will be golden.

ROBERT CROSS · 01-10-2021, 06:27 PM

Quote:

Originally Posted by Mom2twins

The max weight capacity is 1870 on these Carlisle Radial Trailer HD. I wish the garage would have said they weren't right for my trailer. I ordered online.. they came up as an option but the manufactured trailer weight is 3500 lbs. Looks like I need new tires then? I'm supposed to take a short trip about 90 min from this week and not sure it's safe with these tires now though we've made it on 2 other shorter trips fine.

Two 14" GYE's will have a bit more leeway if you do decide to up-grade.

Bob
🇺🇸

Mom2twins · 01-10-2021, 07:08 PM

Quote:

Originally Posted by BayouBiker

I see that the max load is 1870 as you say. That is a per tire load rating. so 3740 max rating. Now the trailer has a GVWR of 3,500 and you have at least 10% and probably 13-15% on th e tongue. Lets use 13% so the weight on the axle is 3,045 lb. You have 695 lb to spare and that is good because you want a minimum 15% margin and 25% if you exceed 68 mph. You have just under 24% margin so you are in good shape with those tires . Do inflate them to max 50 psi cold. So each time you start off you want to be right near 50 psi and you will be golden.

Thank you so much for helping with all the math and numbers. Yes I did look up from my invoice the exact tires with a Load C rating and then did see in the comments online someone else with a "camper" asked a similar question and the axle of 3,045. I didn't take into consideration the tongue. I really appreciate the time and help with this. So far trips with my boys have been fairly close, just to homeschool somewhere away from home. Next summer when we venture across country I will get different tires. Still recovering from all of the initial purchases that go along with this fun adventure! 🤪

I got great advice in this forum with the Dinosaur board to fix the water heater which I did on my own and new I'd get good advice here! 👍 Thank you everyone!

BayouBiker · 01-10-2021, 07:18 PM

Don't let the others scare you away from these tires too quickly, they have good user experience. If you were running Endurance D load, I'd tell you to run them at 50 PSI also and they'd then have the same load capacity. Now if you're planning on scooting down the road in excess of 75 then yes replace them. Me? I'd keep your speed below 68 just as Leslie advised.

CruizinDux · 01-11-2021, 09:21 AM

If I may suggest, here are two links I believe you'll find helpful. IMO bottom line is know your weight per tire. Add 15-20% margin and look at the Carlisle load chart for the rec PSI.

https://www.airforums.com/forums/f43...-167187-3.html

https://www.airforums.com/forums/f43...ml#post2384141

Livermore may have a few scattered County ag scales, certainly over the hill near Tracy, but you can also go to a moving company or find a CAT scale at a truck stop. When I lived in Eugene the Co maintained one near my storage. Only once did I have to wait. Bekin's etc are also not that busy, but the CAT's volume don't give you much time get to know your loading so to speak.

pwlldvd · 01-11-2021, 09:26 AM

Quote:

Originally Posted by McStreamy_

I would not inflate above the maximum rating on the tire unless you want to have a bad day. You should be able to do a quick google search for the type of tire you have and find a load chart that will recommend PSI based on how much weight is on the tire. You always want to include some buffer, but you shouldn't inflate beyond the max rating. And that PSI reading is for a "cold" tire before it's been driven for the day. Just my .02

+1

Find the manufacturer’s chart and use that.

amxpress · 01-11-2021, 09:42 AM

If you look closely at the tire decal located on the left side towards the front, it will state the correct tire size and tire pressure. If the decal states 65 psi and your tires’ maximum pressure is 50 psi, then you have the wrong tires, period. It looks as though your trailer came with Load Range D tires. You purchased Load Range C tires. Which do you want on your trailer?

BayouBiker · 01-11-2021, 10:03 AM

amxpress, it's great to be cautious but it is not correct one must follow the label to the letter. Airstream puts larger load carrying capacity and recommends max pressure for tire reliability. It is true the D range tires at 65 psi are likely to have lower risk of catastrophic failure, but the C rated tires are a safe fit as I explained previously.

I do like your point that the owner must choose between what Airstream believes is the more suitable tire and what the owner now has, and should carefully consider the options.

Hermes · 01-11-2021, 10:12 AM

I switched from the Good Year Marathons to the Good Year Endurance tires (the Marathons are no longer manufactured and the Endurance is a much better tire).
For my model, Airstream recommended 65 psi with the Marathons, which was the max pressure for that tire. With the new Endurance, Airstream now recommends 80 psi for the same trailer which is the max pressure for that tire - go figure.
So I pulled out the Goodyear "LOAD/INFLATION INFORMATION FOR GOODYEAR® ENDURANCE SPECIAL TRAILER (ST) TIRES" (see attached) and the recommended pressure for my trailer is (still) 65 psi.
And from experience, at this pressure there haven't been any rivets popping inside, no dishes on the floor, etc., and it rides smoothly. In addition, when we travel into hot weather, the tire pressure will increase (we have a TPMS) but stays well below the max pressure for the Endurance. No more worries (which was not the case with the Marathons, which had a tendency to blowout).
Happy and safe travels!

Bill M. · 01-11-2021, 11:38 AM

I personally would feel better with the Goodyear Endurance load range D tires on that trailer. That is not scientific. It is my feeling.

MickeyC · 01-11-2021, 01:50 PM

I ran a tire business for years. According to the tire manufacturers you should always go by the inflation rating on the tire. I would run them at 45-50 lbs if that is the max rating. Low pressure creates heat inside the tire. You definitely don't want to exceed the max rating. As already mentioned that could end up badly. Check them in the morning when they are cold.

Good Luck & Enjoy
MC

BandLAir · 01-11-2021, 02:30 PM

If the tires really are ST215/75R14 then they are Special Trailer tires. Roger Marble, who is a retired tire engineer and sometimes posts on this site, runs the RVTireSaftey.net website. I would look up what he has to say, but my understand from him is that ST tires in a trailer application should be inflated at the sidewall pressure. Everything I ever learned about individual wheel loads and load-inflation tables turns to have been for motorhomes and tow vehicles, not trailers. The issue that Roger addresses is "inter-ply shear" and the way to address it is with stiff sidewalls. The tires on my 2020 FC 27 FBT are 80 PSI on the sidewall, and that is what Airstream recommends for them even though, according to the load-inflation table, this is way more pressure than is needed to support the load on the tires. I doubt that Airstream recommends that without a good reason. I run mine slightly lower (72 PSI) to give me a little headroom for ambient temperature variation, but I don't think Roger even thinks that is necessary. I hope he jumps in here. ~Bruce