Correct Tire Selection

[Glorette]

I have recently acquired a 1965 Airstream Safari and have been cleaning renewing and restoring. I have read all of the posts on selecting tires, and my conclusion is that none of the "ST" tires have good reliability. I have found a Goodyear Wrangler AT/D2 light truck P225/75R15 Does anyone have any experience with this tire? Any other recommendations other than the Goodyear Marathon or the Carlisle "ST" tires?

Thanks,

Gene

[LI Pets]

You really should use ST's they are made for the trailer, there are other brands besides Marathons.

[Action]

A tire with the letter "P" in front of the tire size is a passenger vehicle tire. I would not use this tire for a trailer. Light Truck tires will end with a LT.

Tire Tech - Tire Size Information

I am not fond of a ST tire even though it is designed for trailer usage. Only because it is so hot here in the summer. (Arizona) An ST tire will not accept as much heat as a LT tire. An ST tire might work well in Northern climates in the summer and at speeds less than 65 which generates less heat.

While I don't like towing faster than 65, it does occur for me. So my choice in the past has been LT tires. I know this runs in the face of convention wisdom. And I am not sure convention wisdom has been on SR-85 on a Sunday afternoon with 110+ air temps (the asphault is much higher) coming back from Mexico.

>>>>>>>>>>>>>>>Action

[Happycampers]

I am going to replace mine later this summer with 700-R15 there is three companys I know make that size Bridgstone, Toyo and Yokahama.

[LI Pets]

The LT as well as P tires have a much different sidewall construction, they can't take the movement of a trailer in tow as well as ST's.

These 'Special Trailer' (ST) tires have been constructed for better high speed durability and bruise resistance under heavy loads. Trailer tire construction varies substantially from automotive tires, therefore it is essential to choose the correct tire for your towing application. In general, trailer tires have the same load range (or ply) from bead to bead and are bias ply construction. This allows for a stiffer side wall which provides safer towing by helping to reduce trailer sway problems. The use of 'Passenger Car' (P) or 'Light Truck (LT) tires a on a trailer is not recommended because their construction, usually radial or bias belted, allows for more flexible side walls. This could lead to increased trailer sway and loss of control.

Now as to the 65MPH Myths, Legends, Fables and stories

ST's can absolutly go 75 Mph the manfacturer says so.

As long as you don't exceed the load limit of the tire Goodyear for example states

"Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load."




.

[Action]

Originally Posted by LI Pets

ST's can absolutly go 75 Mph the manfacturer says so.

As long as you don't exceed the load limit of the tire Goodyear for example states

"Based on industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph, it is necessary to increase the cold inflation pressures by 10 psi above the recommended pressure for the load."




.

This is interesting. So if one were at the load limit and therefor at max inflation of the tire. What is one to do? Drive at 65? Higher speed does generate higher heat in tires. The environment that my trailer is subjected to has enough heat to start with. And my past experience with ST tires on a 8000# loaded boat trailer was less than my expectations.

Not to knock industry standards, because I support them, however in my personal experience the LT bias ply tires I have used on my A/S have worked well. No sway or lack of control. And may be it's the old bias ply construction that is the biggest influence.

>>>>>>>>>>>>>>>>Action

[LI Pets]

Originally Posted by Action

This is interesting. So if one were at the load limit and therefor at max inflation of the tire. What is one to do? Drive at 65? Higher speed does generate higher heat in tires.

Your not supposed have tires AT the load limit, you need a safety margin.

Using your 8,000lbs trailer with 4 tires that's only 2,000lbs per, I think you can run them at like 40-45 to handle the load.

So to add 10lbs is easy, I think the D range goes to 2550lbs at 65psi

Try reading this
But I think you have your mind made up

[DFK]

This web site Trailer Tires - Tips and Advice by Auto Media has a pretty good description of the design differences (and the reason therefore)between ST tires and others, as well as a discussion of bias versus radial ST tires.

[Action]

Bob,

You are mixing data that I gave out from two different trailers.

The 8000 pound boat and trailer has four ST tires that are rated for something like 2200 pounds each. I consider this to be at max load. I inflate these tires to the max pressure. This was the 3rd boat I had purchased and not the heaviest. The heaviest one I owned was when I lived in Washington State. I have no clue about the tires. I owned it for 4 years and never did much with the tires except to inflate them at the beginning of a trip. And the environment of Washington State is sooooo differnt than AZ. I would bet road temps to be 150 degrees in the summer. And heat kills a tire. I am convinced of it.

My current boat trailer has the ST radial trailer tires. It has only be operated in AZ. One tire on that trailer failed to make the trip to my home from the dealership. I do not know what the inflation was because I did not check the tire pressure when I left the dealership. So it could have been low on pressure which severely increases heat in a tire. This was also in August when the air temps are very high. A year later the tread came off of another tire from that trailer again this was in the early summer. The pressure was checked at an hour earlier at start of the trip to the lake. Then another tire let go of it's tread and I am not sure of the time frame. All of these tires were ST installed either by the dealership or the trailer manufacturer on a trailer that has the load capacity of 9000 pounds. Possible causes may have been age of the tires. (I do not know when they were manufactured becuase I did not know at the time that the manufacturering week was stamped in the tire) Or the first tire the issue could have been caused by lack of proper inflation.

On my A/S it came with very old bias ply truck rated tires. I towed it from Indiana to AZ in July 2002. No tire issues. I have always infalted these tires to max pressure. They were replaced with LT bias ply tire.

I know that ST tires are designed specifically for trailers, and I would not discourage Gene (the original thread starter) from getting this tire design. And in my opinion and experience with ST tires and LT tires. The LTs can take the heat better. And in AZ I have a lot of it to deal with in the summer, my prime towing time. I also know that the majority of trailer tires are usually maxed out for load. (Not so for passenger vehicles) And ST tires carries a 65 mph rating. This is true for me. With a maxed out load capacity and a 65 mph rating I am pushing the limits of ST tires. So I have choosen the LT type of tire because it has worked well for me and offer this experience for Gene and others to make their own decision. Because you are correct I have made mine. (BTW you link does not work)

>>>>>>>>>>>>>>>>>Action

[LI Pets]

Having a shallower tread depth provides the ST tire with two benefits: (1) it doesn't wiggle as much, which can help reduce sway, and (2) it rides cooler, which adds to its longevity.
Generally, the ST tire also has somewhat stiffer sidewalls, especially in its lower section. This reduces sidewall flexing, helping it to track straighter and diminish the risk of trailer sway. The stiffer sides also lessen the risk of sidewall blowout.

[lewster]

Action,

I'm with ya on the LTs! I have had a single axle motorcycle trailer with ST tires that I towed for 3 years....scared to death the whole time that I would have a blowout (not a lot of fun on a single axle!).

Now, I have a 19CCD....again with a single axle. I towed it 8000 miles last summer and watched the inflation pressure and other conditions like a hawk....again always worrying! I have decided to put 16" rims on the CCD along with BF Goodrich 225/75-16 LT LRE tires. I have the same size Michelins on my van and they have given me great service! I have read that the BFGs are just as good at $160 per instead of $230 for the Michelins. At 65psi (or whatever BFG suggests for 2250lbs per tire, I'll be much happier!

Add a Pressure Pro and I'll be set for the big trip!!!

[JimGolden]

You should read the excellent posting on this topic by Mr. Patterson. He went to a BF Goodrich Commercial T/A and has never looked back. I am looking at doing the same. You need to get 16" wheels though. Much better selection in 16" and 17" than in 15" for heavy LT tires.

[lewster]

Originally Posted by JimGolden

You should read the excellent posting on this topic by Mr. Patterson. He went to a BF Goodrich Commercial T/A and has never looked back. I am looking at doing the same. You need to get 16" wheels though. Much better selection in 16" and 17" than in 15" for heavy LT tires.

YUP, Got the rims and trial fitted them........they look great! Tires are on order and should be here by the end of the week. Good excuse to check the brakes and grease the bearings too!

I'll post before and after shots when they are installed.

[ticki2]

A 65 Safari did not come with ST tires , they didn't exist yet . It came with with 700-15 which was a light truck tire . Trailers have used light truck tires for half a century or more. I know of no state law that requires the use of ST tires on a trailer. Because someone has a different opnion does not make one close minded .

[LI Pets]

That was said with tongue 'n cheek

[overlander63]

Originally Posted by ticki2

A 65 Safari did not come with ST tires , they didn't exist yet . It came with with 700-15 which was a light truck tire .

An FYI, if you want the benefit of the radial tire with the sidewall height and construction of the truck tire, you can get 7.00R15 tires, we had an Argosy that came with a set of Michelin XCA 7.00R15D tires. They were so old they did not have a date code anywhere on them, and we had zero problems with them, unlike the ST225 tires we replaced them with.
We have Marathons on our current trailer, more for ease of replacement while traveling than any other reason. If you want to use the LT tires, remember to replace them more frequently than the special trailer tires, as the LT's have less UV resistant compounds.

[Happycampers]

Like I said earlier I am putting 700-R15 LT on my trailer. I don't understand why people think that trailers have to have ST tires and only ST tires. If that is true why are trailer manufacturers going to LT truck tires on all their trailers including 15000 to 18000 lb. trailers. If they work for them I think I will be ok with them for just over 6000 lb.

[ticki2]

Originally Posted by overlander63

An FYI, if you want the benefit of the radial tire with the sidewall height and construction of the truck tire, you can get 7.00R15 tires, we had an Argosy that came with a set of Michelin XCA 7.00R15D tires. They were so old they did not have a date code anywhere on them, and we had zero problems with them, unlike the ST225 tires we replaced them with.
We have Marathons on our current trailer, more for ease of replacement while traveling than any other reason. If you want to use the LT tires, remember to replace them more frequently than the special trailer tires, as the LT's have less UV resistant compounds.

Unfortunately I don't think the XCA is made anymore , on my '76 it was an option . In regard to the UV resistance I must say I'm not convinced . My personal experience tells me otherwise . Last year I replaced two of my tires to match the two from the previous year. The tires that came off were 18 years old according to the date code , they had been on two other vehicles prior , with not a sign of deterioration anywhere . They are BF Goodrich commercial TA 235/75/15XL , and so are the replacements. I've kept them in hopes to find a facility that can test them for any internal damage , for my own edification.

[Beginner]

According to the Michelin Tire Web Site

Michelin Americas Truck Tires XCA Page

They only make the XCA in 17 inch and it is way too large in outside diameter for our trailers with the 22.5 degree axles.
Beginner