tires radials or bias ply tires

[larry b]

I recently purchased a 1975 sovereign and it has bias ply loadmastet 7.00 X 15 tires on it. What is better staying with original bias ply or going with a radial tire. Not sure if they make radials in 7.00 X 15 so what size radial should I look for if its a better choice.

Going to buy tires in the spring an want to make the right decisions. I have read many threads on tires but really still not sure what the right choice is.

[jjustice]

I had the same issue when my wife and I bought our '78 Argosy. The bias tires were old and cracked and the trailer had the original wheels but in talking around I discovered that the old wheels do not work well with radial tires. So you have a choice to keep your bias tire configuration or change to radials which will necessitate getting new wheels. My experience and opinion.

[easyride]

Originally Posted by jjustice

I had the same issue when my wife and I bought our '78 Argosy. The bias tires were old and cracked and the trailer had the original wheels but in talking around I discovered that the old wheels do not work well with radial tires. So you have a choice to keep your bias tire configuration or change to radials which will necessitate getting new wheels. My experience and opinion.

Never heard of that before,I`m running radials on all my trailers,granted the 77 gets almost all the mileage,but no problems.
The tires I am running are 235/75 D-rated.Dave

[Inland RV Center, In]

Originally Posted by larry b

I recently purchased a 1975 sovereign and it has bias ply loadmastet 7.00 X 15 tires on it. What is better staying with original bias ply or going with a radial tire. Not sure if they make radials in 7.00 X 15 so what size radial should I look for if its a better choice.

Going to buy tires in the spring an want to make the right decisions. I have read many threads on tires but really still not sure what the right choice is.

Which tire is easier found, when you travel?

More than likely the radials.

Traveling also requires a little extra planning, for that "just in case it happens".

Staying away from odd ball and local only stuff pays big dividends, if you need a replacement whatever, should you be miles away from home.

Goodyear Marathon is the tire Airstream still uses. The proper radial for your Argosy is ST 225/75 R15.

You can use load range "C" if you wish.

Unless the old tires are 8 ply, you must not increase the rating to a "D", as the wheels could split.

Wheel manufacturers all say that once a wheel has been in service for a long time, with as an example in this case, a load range "C" you cannot increase the tire rating to a "D" as the wheels can split.

Andy

[Ahzmyrah]

This may be filed under TMI (too much information) Andy is right there are more radial tires out there than bias ply these days. There is no good reason to use bias ply tires unless you just want a true "Vintage" look.
Bias ply tires will take a set when parked for extended periods. I'm old enough to have owned vehicles that thumped along on flat sided bias tires until they warmed up enough to get round again. Also, bias ply tires have a tendenecy to roll over or lift up the inside part of the tire tread when cornering this means less rubber is in contact with the road when you need it the most going around curves on wet or slippery roads. There are good reasons why radials have all but replaced bias ply tires these days and cost is not one of them. Radials are more expensive to build but they are better tires.

Wheels - the inside of wheels in the USA are stamped with a weight rating. Tires are also assigned weight ratings i.e. Load ranges B,C,D,E and F. Each load range has a maximum air pressure rating D for example is 65 psi. and E is 80 psi. The maximum load the tire is rated to carry is also stamped into the tire sidewall. The DOT (Department of Transportation) makes these rules that all tire and wheel manufacturers must comply with. So if you know the max load your wheel will support and use a tire that does not exceed the load limit of the wheel it should not fail because of excess air pressure.

The GVW of your rig determines what tires you need to have. Your A/S has 4 tires, divide the GVW by 4 and look for a tire load range that will exceed that number with a safety margin, make sure your wheels will support the load the tires are rated for and you are golden.

[wingfoot321]

You have already received good advice.

My trailer is a 87 Sovereign 29ft vs your 31ft. Not much difference.

The equivalent metric size for the 700-15 is the 235/75R15 which is an LT or light truck size. This is a van size tire.

I defer to Andy on the rim stressing after many years.

I have ST225/75R15 loadrange D Goodyear Marathon on my trailer. I load out at 7300# less hitch weight of 810# (approx), therefore 1623 lbs per tire. The D load range tire is 2540 # at 65psi. I am loading the tire at approx 64% but, my tires are 4 years old this year. I like the extra safety factor as I plan to go at least 6 years.

Also, a big difference with radials is the steel belts. When they run over debris, they have a much better chance of turning a nail etc. without getting a penetration through into the air chamber. Radials also generate less rolling resistance and run cooler due to no cross plies and the belt package.

My current set of tires have been to British Columbia,Alberta, New Foundland, Southwest, Southeast, Texas or Florida for winters, and Alaska this summer.

I never ride my trailer on the side of the road. I am an old bicycle rider and I remember how much trash gets deposited beyound the edge white line.

[Pick]

I've got bias ply on my coach. I've got Marathons on my flatbed equipment trailer. The Marathons are all cracking on the sidewalls. The bias ply still look like new and have no cracks. They are both 5-6 years old. Marathons seem to run cooler, though.

[larry b]

thanks all for the info. I am planning on going with radial. 225-75-15 is this the right size to replace 7.00 x 15??????

I have also read nothing bad on Maxxis tires and have read several dissapointment on Marathons.

[Inland RV Center, In]

Originally Posted by larry b

thanks all for the info. I am planning on going with radial. 225-75-15 is this the right size to replace 7.00 x 15??????

I have also read nothing bad on Maxxis tires and have read several dissapointment on Marathons.

It all has to do with how many tires are out there.

Maxxis, not many, Marathons, hundreds of thousands.

If you take even a one percent failure rate, obviously Maxxis will score less.

But, Maxxis is also not known around the RV industry, nearly as well as Marathons. Then add to that, that the Marathons were not made in the USA for a while.

Andy

[AirsDream]

Maxxis v. Goodyear ... I went through same debate two years ago. Local dealers all "could get" Maxxis "in a few days". Marathons in stock or same day. You're not too far from me - call around and see what they tell you. I think you'll hear the same thing. So now imagne that you have a shredded tire and a bum spare one day out in East Tumbleweed ... how long you want to sit and wait out there to get a new tire? Which are you gonna' get sooner?

The received wisdom is that Goodyear had a lot of QC problems when they started manufacturing in China, and there were a lot of on-road failures, even considering their dominance in the field. I figured they've got it worked out by now. So far, so good ... I've probably got less than 5k miles on the Marathons, but no issues ... yet. Like anything else, you do need to check the pressures regularly, and I check temps of tires and hubs every stop, just to make sure nothing's geting hot. YMMV. Good luck.

[Inland RV Center, In]

Replacing the air in the trailer tires, with Nitrogen, helps keeping the tires cooler, and far less variation in pressure.

Costco now does it in all the tires they service.

Andy

[wingfoot321]

Larry,

One small issue. There is no direct size equivalent to the 700-15 in a trailer tire. The closest size is the ST 225/75R15 LR C or D. You can look on either Michelin or Goodyear websites and they will have charts showing OD. My best recollection is that the 700-15 stands about a 1/2 inch taller than the 225/75R15.

The LT235/75R15 LR C (I don't think this tire is made in a D) is the equivalent of the 700-15. Only problem is not having the reserve load capacity of the LR D. Some folks are opting to purchase a Michelin in this size, LR C and betting that Michelin's quality & uniformity are sufficient to have this tire hold up even though it is loaded heavier as a percentage of total. 2150# LR C vs. 2540# LR D.

Other folks are opting to replace their wheels and move to 16" diameter so that they can purchase a LT (light truck in a LR D).

Sorry, don't mean to complicate things. I have been telling my friends at airstream for 2-3 years that Airstream should move up to a 16" wheel standard. I am sure price is a major consideration due to the number of cheaper trailer tires coming in from China.

LT tires are tested to 80 mph vs 65 mph for ST tires.

[mitsy]

is the tire for a tradewind the same size as other airstream models?

[Inland RV Center, In]

Originally Posted by wingfoot321

Larry,

One small issue.

Sorry, don't mean to complicate things. I have been telling my friends at airstream for 2-3 years that Airstream should move up to a 16" wheel standard. I am sure price is a major consideration due to the number of cheaper trailer tires coming in from China.

A 16 inch tire, as the axle rubber rods age and give out, will get very close to hitting the top of the outer wheel well, especially when hitting some good bumps.

Part of that reason, is the starting angle of the axle torsion arms that Airstream specs out.

Andy

[Inland RV Center, In]

Originally Posted by mitsy

is the tire for a tradewind the same size as other airstream models?

Yes.

For your trailer, ST 225/75 R15 load range C

Andy

[MRHottinger]

Ok so I am a newbie on the board, but I know something about tires. I use to work for PACCAR, they build Kenworth and Peterbilt trucks around the world. I worked in the parts division and also was a supervisor in the roadside services call center. I have spent many hours with tire people ranging from recappers to top of the line Michelin people and learned a lot about design and rubber compounds. I have seen people post about using LT tires on their AS. You wont catch me doing that as I have had a blow out that cost me more than a tire in repairs. You see ST tires are built for trailers. The compound is different and the sidewalls are different from LT's. Some say, "why would they do that?" Well you see trailers tend to kiss curbs or drop off edges more often the cars and when you figure the stress and pressure put on a sidewall on a trailer it is a lot. No, i dont have a number for a lot any more but I have seen fluid dynamics testing demonstrating it. On the other hand how many of us have had to cut it hard and tight to get into the camp site or storage space you keep your trailer at? What do you think is happening to your tires on the trailers as the axles are forced to work against each other? Ok, the single axle guys get a pass on this. Thats right, check the asphalt around the trailer when you turn around in a parking lot or into a parking spot, your tandem axles just left a couple of black marks. I have friends with a $60,000 Open Road 5th wheel that when the storage people parked it, using a small yard tractor, they bent the frame and an axle totaling the camper. Yes it is a 12,000lb camper but it is the same thing. ST tires are build to handle the abuse we can dish out as eager Americans to hit the open road and relax in our campers. I thought I would pass this on because, unlike me just starting and buying a 35 yo starter AS, some of you have some incredible pieces of art in restored unis and other have newer units over $50k. You bought the best camper in the world, treat it like you love it. I am a big guy and to protect my feet I by the right shoe for my feet, not just what ever I find that is round and fits me.

Ok, off my soap box now... I prefer ST radials for the temps at high speed but bias tires will serve your purpose too. Just dont expect to find them easily why driving across rural America and you need a new tire.

[barts]

The forces due to turning a dual axle trailer cannot be any higher than those caused by fast cornering as both are limited by friction.

Trailer tire sidewalls can indeed get abused by inattentive drivers - but the same is true for trucks, particularly 4wd.

There's nothing magical about ST tires... and considering the number of blowouts & separation problems people describe, I'm taking my chances with Michelin LT tires - just like my trailer came with new nearly 40 years ago.

- Bart

[Mexray]

The forces due to turning a dual axle trailer cannot be any higher than those caused by fast cornering as both are limited by friction.

Bart,

I have to disagree here - during 'fast cornering', the rear tires on multiple axle trailers are tracking the forward tires...during low speed turning, as in maneuvering around a parking lot at extreme angles, one set of tires (if not both) are always being 'scuffed' as evidenced by the 'rubber marks left on the road'....

I'm also in the 'bias ply' camp for our 78 AS...we're using 7.00 -15's as per original, and they weren't difficult to find at all...this size bias ply tire has been around for ages, and is still popular on all kinds of smaller trailers - you can find all kinds of tires in this size on the web...

Bias ply tires 'track' great for trailers, their intended purpose - sure, they do have some limitations (rolling resistance, etc.) as noted above when compared with radial types, but it's hard to argue with success -

I think MRHottinger's correct, trailer tires are built to take much more sidewall punishment than LT radials...LT's can easily get their sidewalls damaged, just ask your buddy with that new pickup that runs some rocky trails, I seen it more than once - a sharp rock, etc., can bruise or puncture those vulnerable sidewalls...

BTW...MRHottinger - I dealt with your old employer, PACCAR for many years from the Late 60's to the mid 80's, running the parts dept. for the KW dealer in the SF Bay Area - lots of memories from those years, meeting other Parts Mgr's from all over the country, and the occasional visits to Seattle, KC, Chillicothe, etc...some great times...

Regards, Ray

[MRHottinger]

Bart, I was like you and felt all was the same. Step into a fluids dynamics lab and you will be surprised. There a a big differance in sidewall abuse as LT side wall flex leads to more instability in panic turn situation (nobody ever wants to be there), trailer ride (will bounce more) and how much they roll under in tight turn scuffing the side more. LT tires are not built for high speed turns, they are built to give and forgive on rough terrain to give the most traction available. Even the standard LT tire is not adequate for somebody going to the rough trails, they may tires that resist sidewall damage from sharp rocks too. My truck I built while living in Colo Spgs had 2 sets of tires. everyday 4x4 LT tires and my trail tires and at that time I did not know what I know about tires now. Performace tires are built for high speed cornering and that is a different story too because the sidewalls are tougher, ride rougher and have a soft compund that scuffs off fast. Also TR compounds are built to give you the least rolling resistance while towing and the longest tread life in high scuff situations.

If you notice the tires on tractor trailer application you will see a differance as they have 3 types of tires; steer tires, drive tires and trailer tires. Now I have seen many people put used steer tires on trailers to get by but the real fleet manager will not put drive tires on trailers. Steer tires are built for low rolling resistance and stiff sidewalls for hard full lock tire scuffing turns. Drive tires are built for heavy traction application as well as load but not as much shoulder design because they seldom have to roll on the sidewalls, rolling resistance is higher. Trailer tires are built to be followers, straight and true, have enough sidewall strength to resist the heavy forces applied during dock parking procedure and yet give a smooth ride and very low rolling resistance.

Almost last note. I have seen the testing but cant speak confidantly about is that TR compounds are built to resist UV deteriation more that Passanger and LT tires because they tend to be parked for longer periods of time with constant abuse from the sun. I might believe that but I also think all name brand manufactures build the tires with UV resistance built in. I have put a few miles on my trailer between the coasts and in the midwest and have went through a 4 sets of tires and have had two blow outs, one LT and one POS TR that we all know had problems.

Again, seeing a tire at work and watching the colors change in a fluid dynamics lab is awesome. The tires are built for the application I would love to work in a lab like that but then I hate math so maybe I could just clean the place up. Disclaimer: this is radial information only, bias is a whole different world and if the technology works why worry.

IMHO-- Ultimately we are responsible owners and will use what we like and trust. So lets keep on the good fight and spend many happy miles and nights in our homes away from home, well in some cases - just home!

"BTW...MRHottinger - I dealt with your old employer, PACCAR for many years from the Late 60's to the mid 80's, running the parts dept. for the KW dealer in the SF Bay Area - lots of memories from those years, meeting other Parts Mgr's from all over the country, and the occasional visits to Seattle, KC, Chillicothe, etc...some great times..."

Yep, Ray I miss it some too. In Seattle I was a Call Center Supervisor, Regional Manager for National Maintenance then moved to Georgia to be Distribution Manager at the warehouse then to Regional Manager for PACCAR Brands in TN/KY/OH/WV/VA/MD/DE. Been to all the facilities in US and 3 outside the US. Miss it some because some of the PM's were crazy.

[crispyboy]

So has anybody have experience with Carlisle tires? Good/bad/indifferent? I have them on a 4 wheel utility trailer and didn't have trouble until they were 7 years old. I replaced them with the same load range "C" Carlisle tire - $59 each last summer. Just curious if these would be good enough for the travel trailer.