No need to switch load ratings for ST tires?

[Atlee]

I'm getting a "new to me" 2012 Koala 21CS tomorrow. It has Goodyear Marathon ST205/75R14 C tires.

I know a lot of folks are either wanting to go up in tire size, or at least in load rating. I understand it usually due to the small margin between the GVWR of the TT and the load rating of the 4 tires.

In my situation, the trailer's GVWR is 4950#, and the load rating of the 4 tires is 7040# for a margin of 2090#. In this case, the weight margin of 2090# should be more than enough, and I shouldn't automatically look for a higher load range tire. Correct?

[jadatis]

If you can find something like this on the tire "maximum load xxxx lbs AT yyy PSI(cold)" then that are the data I need to fill it in in my Traveltrailer-tirepressure calculator.
Then make shure the GVWR you mentioned is the real GVWR , as discussed already.
The C at the back probably means C-load wich is in America 50 psi reference-pressure, wich is not the maximum pressure, But if GVWR is right you dont need that much . A highening up can be better because of the ST tires wich are calculated for more deflection of the tire wich they may have at lower speed of 65m/h. But it would be better to handle it the same as an LT tire , if you have the reserve you have. This makes the advice higher.
So give the data , and I will calculate.
If you want to try yourselves, download by RICHTclicking on the newest version of my Calculator in next map on my skydrive.
https://skydrive.live.com/?cid=a526e0eee092e6dc#cid=A526E0EEE092E6DC&id=A526E0EEE092E6DC%21793

[steelpony5555]

If you're under 10k lbs ST tires should do fine as long as you keep an eye on the tire pressure. Once you get up over 10k and the bigger 5er's are when you'll have a problem with blowouts. Although if you have 14 inch tires I would and I did go up to 15 inch tires.......

[Chuck_Gail]

You are good to go. No reason to up Load range, which USUALLY requires buying new RIMS in order to be safe.

[JIMNLIN]

Your trailer has a 4950 GVWR. You may have 600 lbs of hitch weight which leaves around 4350 lb on the trailers axle/tires. Divide by 4 tires = close to 1100 lbs on each tire.

Tire experts tell us a 15-20 percent reserve capacity for a tire on a trailer works best.

Your ST205/75-14 C have a good 28-30 percent per tire reserve capacity which is a large amount for a trailer that small. You have no worries other than finding a ST tire that has a proven track record.

Looking around the net on the many different trailering forums the Maxxis ST8008 has the inside on best reliability of the ST tires.

[JJBIRISH]

Atlee wrote:
I've come to that conclusion, that the current 205/75R14 LRC ST tires are fine. The only question remaining is which brand of ST tire to put on the "beast".

My current trailer is a 2009 HiLo Towlite 22' trailer which has 15" LR C, GY Marathons on it. They are nearly at the end of their useful life. They were built in early 2009. I've had zero trouble with them, and they've held the proper air pressure over extended periods. I always put the max air pressure called for by the tire, in this case 50 psi.

The interesting thing is two of the tires on the ground are US made Marathons, and the other two are China made Marathons. And even more interesting is the US made tires are a few weeks newer than the China made tires. There was probably a period of time when the production was overlapping, before US manufacture ceased altogether.

skipnchar wrote:
My 8,000 lb. Rockwood has traveled over 90,000 towing miles on it's OEM 6 ply tires (C rated ST). I"ve had one flat and one tire cut completely in half from road debris (larger or going to 8 ply tires would not have prevented either). Also check the number of posts where folks have gone to overrated tires (moved up to a D or E rated tire) and still have blowouts. Blowouts are NOT caused by using the correct size tire provided you're not overloading your trailer. SOME brands are just poorly manufactured. I say this after WATCHING two different brands of ST tire blow up while sitting on the bumper in the spare tire position. Kind of hard to lay that on overloading 🙂
Good luck / Skip

GY moved the ST tire production to china, had problems with the tire enough to move production temporally back to the USA and then back to China again… no doubt there were some overlapping sales…
I Never read they pulled the problem tires out of the distribution chain, but I have read they ran a secret warranty for a time because of them…

[Atlee]

I've come to that conclusion, that the current 205/75R14 LRC ST tires are fine. The only question remaining is which brand of ST tire to put on the "beast".

My current trailer is a 2009 HiLo Towlite 22' trailer which has 15" LR C, GY Marathons on it. They are nearly at the end of their useful life. They were built in early 2009. I've had zero trouble with them, and they've held the proper air pressure over extended periods. I always put the max air pressure called for by the tire, in this case 50 psi.

The interesting thing is two of the tires on the ground are US made Marathons, and the other two are China made Marathons. And even more interesting is the US made tires are a few weeks newer than the China made tires. There was probably a period of time when the production was overlapping, before US manufacture ceased altogether.

skipnchar wrote:
My 8,000 lb. Rockwood has traveled over 90,000 towing miles on it's OEM 6 ply tires (C rated ST). I"ve had one flat and one tire cut completely in half from road debris (larger or going to 8 ply tires would not have prevented either). Also check the number of posts where folks have gone to overrated tires (moved up to a D or E rated tire) and still have blowouts. Blowouts are NOT caused by using the correct size tire provided you're not overloading your trailer. SOME brands are just poorly manufactured. I say this after WATCHING two different brands of ST tire blow up while sitting on the bumper in the spare tire position. Kind of hard to lay that on overloading 🙂
Good luck / Skip

[Atlee]

The GVWR is the max amount the trailer is supposed to weight including any and all water, food, pots & pans, clothes, and other stuff. If DW fills up all storage spaces, and I have a full tank of fresh water, the trailer can only weight 4,950#.

I would not expect to have the trailer actually weight that much when packed and ready for the road. I'm just looking at worse case situation.

It will never just weight roughly 3450# since that is the factory dry weight. And from the actual built weight stickers on Koala's, the factory adds roughly 300# plus of "required options" before shipping.

JaxDad wrote:
I think the numbers are somewhat confusing, the number you're looking at is the gross weight rating, that is what the manufacturer says is the maximum the trailer can weigh. It has very little to do with what the trailer's actually going to weigh going down the road on those tires.

From what I could find it seems the base weight of that trailer, what it weighed rolling out of the factory, is about 3,450 pounds.

If that's the case, you have (aside from what you load into it) tires rated for double what the trailer actually weighs.

IMHO a 100% safety margin is plenty.

[skipnchar]

My 8,000 lb. Rockwood has traveled over 90,000 towing miles on it's OEM 6 ply tires (C rated ST). I"ve had one flat and one tire cut completely in half from road debris (larger or going to 8 ply tires would not have prevented either). Also check the number of posts where folks have gone to overrated tires (moved up to a D or E rated tire) and still have blowouts. Blowouts are NOT caused by using the correct size tire provided you're not overloading your trailer. SOME brands are just poorly manufactured. I say this after WATCHING two different brands of ST tire blow up while sitting on the bumper in the spare tire position. Kind of hard to lay that on overloading 🙂
Good luck / Skip

[coolbreeze01]

I went one size larger and increased two load ratings. Not for capacity, but peace of mind. Its worked for the last 12,000 miles :C

[JaxDad]

I think the numbers are somewhat confusing, the number you're looking at is the gross weight rating, that is what the manufacturer says is the maximum the trailer can weigh. It has very little to do with what the trailer's actually going to weigh going down the road on those tires.

From what I could find it seems the base weight of that trailer, what it weighed rolling out of the factory, is about 3,450 pounds.

If that's the case, you have (aside from what you load into it) tires rated for double what the trailer actually weighs.

IMHO a 100% safety margin is plenty.

[BurbMan]

In theory....load the trailer for camping and then get it weighed. Also be sure to keep the suspension lubed, equalizer link in good working order, and tow the trailer as level as possible. Even though you are under ratings overall, that doesn't mean that the load is distributed evenly among all 4 tires.