Trailer Tires

[Lumatic]

I need some new tires for my 71 Tradewind. I'm looking for advice about 6ply vs 8ply etc.

[scottanlily]

My advice would be to get 8 ply D range tires ,many many threads and opinions on whats best ,type of tire, and so on .Id do the"search function" and research the threads for more ideas .

Scott

[Beginner]

Marshall
What type (LT, P, ST), size and ply rating (load range) is on the trailer now?
Do you have a shop manual on the trailer? If so, what size/type does the manual list?
Beginner

[toadtogo]

My choice was to go with Maxxis ST 8 ply D range, not that the AS needed the weight rating, but because the same is on my other trailer which does need the weight rating. So now, I have 8 tires of the same size and rating that I can "move around" if needed.

So, my opinion is to look for what you are comfortable for your Sovereign and match them up.

[Lumatic]

Beginner
The current tires are very old, perhaps original 1971. They are 7:00x15 Load Range C. I can't see the ply info. The manuals don't have specs but speak of using 6ply or 8ply tires. I also wonder if 10 ply tires are overkill. I regularly see these on Ebay under an Airstream search. Thanks

[AlbertF]

I believe the original tires were light truck tires (LTs). Special Trailer (ST) tires came along later. Load range C is equivalent to the old 6 ply rating. You can find some LT 7.00x15s today - Toyo and a couple of other companies still make them. Most people, however, seem to buy ST225/75/15s, in Load Range D. Load Range D will give you a load capacity in excess of 8,000 lbs at 65 psi.

[Lumatic]

Originally Posted by AlbertF

I believe the original tires were light truck tires (LTs). Special Trailer (ST) tires came along later. Load range C is equivalent to the old 6 ply rating. You can find some LT 7.00x15s today - Toyo and a couple of other companies still make them. Most people, however, seem to buy ST225/75/15s, in Load Range D. Load Range D will give you a load capacity in excess of 8,000 lbs at 65 psi.

Sooo, given my Tradewind weighs less than 4000# is there a reason I should use Load range D or 8 or 10 ply tires, or does it really make any difference? Converesely, is there any reason why I should stick with the 6 ply / Load Range C tires?
Thanks

[Inland RV Center, In]

Originally Posted by Marshall

Sooo, given my Tradewind weighs less than 4000# is there a reason I should use Load range D or 8 or 10 ply tires, or does it really make any difference? Converesely, is there any reason why I should stick with the 6 ply / Load Range C tires?
Thanks

If the tire you have had on the trailer were 6 ply, you "cannot" change them to a higher rating.

To do so will split every wheel you use them on.

This is as per "every wheel manufacturer."

If you want to use 8 ply, that's fine, but you must change the wheels.

You must not ever use 10 ply wheels for an Airstream trailer.

Case in point. One of our customers was told not to put 8 ply tires on wheel that had 6 ply tires on them for years.

He said "BS." and left in a huff.

He went to a local dealer and in fact did install the 8 ply tires.

He called us from Phoenix, some 350 miles away, after a couple of days. He said "he should have listened, as he replace three of his wheels already, because they indeed split, just like he was told they would."

Andy

[scottanlily]

Well ,that certainly does tell the tale on that .andy is correct ,use the 6
ply load C tires ,you have four so it'll be plenty capacity.Ten ply are way
too stiff and rigid ,my 60 trdwnd is a single axle D rated bias tires ,I wouldn't
put 10 ply on it .Those E bay 10 plys have been on there listed for a couple
years now ,someone must have a stack of them they can't get rid off .

Scott

[Lumatic]

Originally Posted by Inland RV Center, In

If the tire you have had on the trailer were 6 ply, you "cannot" change them to a higher rating.

To do so will split every wheel you use them on.


Andy

Thank you Andy
Once again I am dazzled by your encycopedic command of Airstream tech miscellany. This makes sense to me and will follow your advice. I think I will keep the original rims as there are 4 cool baby moons that are original and came with the coach. I don't know if they will fit new rims.

I still have not found the ply rating on these tires altough they definitely do say Load Range C. They are old, perhaps as old as the trailer (1971), quite weather checked and no doubt rotten. I consider myself lucky that they held together for the 25 mile 25mph tow from the the field I found this mouse condo to my backyard. Perhaps the ply rating label is sitting in the dirt on all 4 tires.

Can I assume that "Load Range C" equals "6 ply"?

[Inland RV Center, In]

Originally Posted by Marshall

Thank you Andy
Once again I am dazzled by your encycopedic command of Airstream tech miscellany. This makes sense to me and will follow your advice. I think I will keep the original rims as there are 4 cool baby moons that are original and came with the coach. I don't know if they will fit new rims.

I still have not found the ply rating on these tires altough they definitely do say Load Range C. They are old, perhaps as old as the trailer (1971), quite weather checked and no doubt rotten. I consider myself lucky that they held together for the 25 mile 25mph tow from the the field I found this mouse condo to my backyard. Perhaps the ply rating label is sitting in the dirt on all 4 tires.

Can I assume that "Load Range C" equals "6 ply"?

You are correct.

4 ply = B
6 ply = C
8 ply = D
10 ply = E (enough already, way way too much for "any" Airstream trailer ever built.

Andy

[TomW]

Originally Posted by Inland RV Center, In

You are correct....10 ply = E (enough already, way way too much for "any" Airstream trailer ever built.

Andy is seldom wrong.

This post in this thread is worth reading for vintage Airstream owners trying to reconcile what the owner's manual says versus what is commonly available.

[ticki2]

Originally Posted by Inland RV Center, In

If the tire you have had on the trailer were 6 ply, you "cannot" change them to a higher rating.

To do so will split every wheel you use them on.

This is as per "every wheel manufacturer."

If you want to use 8 ply, that's fine, but you must change the wheels.

You must not ever use 10 ply wheels for an Airstream trailer.

Case in point. One of our customers was told not to put 8 ply tires on wheel that had 6 ply tires on them for years.

He said "BS." and left in a huff.

He went to a local dealer and in fact did install the 8 ply tires.

He called us from Phoenix, some 350 miles away, after a couple of days. He said "he should have listened, as he replace three of his wheels already, because they indeed split, just like he was told they would."

Andy

Andy ,
This is by no means a flame , can you point me to the source of this information about wheels cracking . I have never heard of this before . In my 50 years of driving I have changed ply ratings of tire on the same wheels many times and never had a problem . Any info would be helpfull , thanks.

[JimGolden]

I'd heard you could break a wheel apart if you run too much pressure. Maybe that's how he split the rims; the Load range D tires can take a higher pressure than the Load range C tires can. So if he inflated the tires up to their D pressure, then he probably exceeded the capacity of the wheels and thus split them apart.

Is that how it works Andy?

Man that'd be a bad thing to be going down the road and you actually blow your wheel apart!

[Beginner]

The problem is not the capacity of the tire (load range D) but the tires ability to resist heat. The higher the speed rating the more heat the tire can build and survive.
Load range E ST tires (80 PSI I believe) will probally survive 65 to 80 mph because at 80 psi, given the weight of the Airstream, the sidewalls will not be flexing very much(thus not generating much heat internally). This in my mind is why GoodYear recommends adding as much as 10 PSI above the max pressure recommended on the sidewall when you are going to be traveling at speeds above 65 MPH. This added pressure will decrease the amount that the sidewall will be flexing (thus generating less internal heat).
You've bought the best, most durable piece of RV equipment available. Why take a chance on tearing it up with tires that do not have the capability of withstanding our present driving habits?
The choice is ours.
Slow down or go to different tires.
Its that simple.
Beginner

[Lumatic]

Originally Posted by Beginner

The problem is not the capacity of the tire (load range D) but the tires ability to resist heat. Load range E ST tires (80 PSI I believe) will probally survive 65 to 80 mph because at 80 psi, given the weight of the Airstream, the sidewalls will not be flexing very much.
Beginner

The thoughts that have been running through this thread seem to support not really needing a higher load range tire on my 25' 3500# tandem axle Tradewind. Maybe it would be more appropriate on a MH, a Sovereign, or a big 34' triple?

I think another factor may be driving down the road it is a lot easier to find a tire pump that can pump my tires up to 45# than 80#.

Do you think?

[davidz71]

Originally Posted by Beginner

...This in my mind is why GoodYear recommends adding as much as 10 PSI above the max pressure recommended on the sidewall when you are going to be traveling at speeds above 65 MPH. This added pressure will decrease the amount that the sidewall will be flexing (thus generating less internal heat).Beginner

Do not add more than the max psi noted on the tire! This is max cold and you can expect the tire to heat up which will increase the psi anywhere from 2-5 psi or more. P (passenger tires should not be used on your trailer, ST trailer tires are OK and folks are having good luck with LT in the B.F. Goodrich Commercial 16" tire on 16" rims.

I'm running the standard Goodyear Marathon ST 225-75-16 in C rating and tire pressure is 50 psi. I do have one D rated Marathon mixed in the bunch and have found that when aired the same as the other 3 C rated tires, that tire runs 2-3 psi higher when at highway speeds. A D rated tire calls for 65 psi max but I sure wouldn't run that on my Sovereign and didn't do so on my 31' Excella 500.

The ST tire is rated for max speed of 65 mph and because of this, I do not exceed 65 mph when towing any longer. I have put over 5,000 miles on the Marathons since purchasing the trailer over 2.5 years ago and 3 of those tires probably had at least 2,000 miles on them prior to purchase.

In summary, many have gone to D rated tires for additional weight handling and safety but for our size/weight trailer, why do that? If you have weighed your trailer and it is within the specs of a Goodyear Marathon C rated tire then stay with the C and not have to buy new rims.

[Beginner]

Marshall
I currently have Load Range E tires (Dunlop Radial Rover AT LT245/75R16 Speed Rating R(106 MPH))on my tow vehicle(1990 GMC Rally STX 3500). Fortunately they have been there for a number of years and replacment is looming soon in their future.
Because of the amount of weight that is on each axle, as determined by the local CAT Scale, I will be dropping back to Load Range D if I can(if there are available), which by the way was the rating of the original tires on the van when I got it.
I plan to go to Michelins.
I expect a softer ride.
Beginner

[Beginner]

Read this web site:
http://www.goodyear.com/rv/pdf/marat...nfo_032806.pdf
Says "The cold inflation pressure must not exceed 10 psi beyond the inflation specified for the maximum load of the tire".
SO, if the tires are fully loaded then go 10 PSI above the recommended max pressure on the sidewall ONLY IF THE WHEEL CAN STAND IT.
This does not give me a warm fuzzy.
Beginner

[ticki2]

Originally Posted by JimGolden

I'd heard you could break a wheel apart if you run too much pressure. Maybe that's how he split the rims; the Load range D tires can take a higher pressure than the Load range C tires can. So if he inflated the tires up to their D pressure, then he probably exceeded the capacity of the wheels and thus split them apart.

Is that how it works Andy?

Man that'd be a bad thing to be going down the road and you actually blow your wheel apart!

This I agree with , you should never excede the pressure or load rating of the wheel . I got the impression that what was being said is that going down in load rating would cause the same problem .