bias ply or radial tires

[Mr.Gauch]

Hi everyone,

I have read most of the post regarding tires. I've got a newly acquired 1300 '70 boler that has been sitting for about ten years in a field. It has 155/80/r13 on it right now that are fairly weather cracked so i am in need of new tires. I will most likely got with the recommended ST175/80/R13 tires but no one has mentioned whether radial or bias is best. Im thinking that bias ply tires would make the trailer pretty bouncy on the road going over bumps and such, but think that radials will make the suspension to stiff and produce the same results. Anyways, what are your suggestions/comments.

Thanks
Tyler

[lamimartin]

Originally Posted by Mr.Gauch

Hi everyone,
(...) Im thinking that bias ply tires would make the trailer pretty bouncy on the road going over bumps and such, but think that radials will make the suspension to stiff and produce the same results. Anyways, what are your suggestions/comments.
Thanks
Tyler

Radial tires or bias tires can both be used if the load rating and proper inflation is respected. Regular car tires are a very poor substitute. Their load rating is often barely sufficient and they are too flexible to prevent sway, which is potentially very dangerous.

I use ST (small truck - "trailer service") 6 ply radial tires on my 15" Trillium and I see no use for my sway bar so far ! In my humble opinion, it is not worth to settle for less than 6 ply radial or Bias tires. Bias are cheaper and may last as long as radials. Radials are likely to be smother and reduce vibrations, but to which extent ? Examples: http://www.atvandtrailertires.com/trailer_catalog.pdf

High loads, side winds, bouncy curves are all potential causes of sway that are minimized when your tires sides are stiffer with 6 ply. Cheaper softer (4 ply) sides tires will cause your tires to wear prematurely on edges, increasing chances of flat tire or blowout. They won't last and will make the ride quite more stressfull.

[Radar1]

My Scamp came with radials and I replaced those with radials. I upgraded to "D" rated tires that can carry more air pressure and have a higher load capacity.

[lamimartin]

Originally Posted by lamimartin

Radial tires or bias tires can both be used if the load rating and proper inflation is respected. Regular car tires are a very poor substitute. (...) I use ST (small truck - "trailer service")...

ST stands for Special Trailer or Trailer Service, but not "Small Truck" (thanks to Brian B-P).

I understand that many of us use regular car tires (I have one as a spare), but I clearly prefer to exceed the minimal load capacity car tires offer compared to ST tires. I've experienced more sway and bouncing on tent trailer I previously had simply because I used the cheapest 4 ply trailer tires. The closer you are to the rated limit, the higher the risk of trouble in my humble opinion. Consequently, shorter and lighter RV may not need 6 ply and may do with car tires, but I think my 15' Trillium 4500 is too heavy with the added equipment to take any chances with the tires. I like it just the way it is.

I also want to point out that the link to DURO tire catalog is not an endorsement of any kind, but only an example of what was commonly available as Radial, Bias, 4 and 6 ply tires in the dimension he was looking for (ST175/80/R13). There might be better brands, but I think targeting a few brands 6 ply tires in that dimension is a good idea.

I hope this will help clarify the matter and forgive me if I confused someone with my opinions based on my own experience.

[lamimartin]

Interesting information about Special Trailer Service tires from Tire Tech Information - Load Range/Ply Rating Identification

Special Trailer Service tires are often available in multiple load ranges. The appropriate load range is identified immediately following the size's rim diameter in Tire Rack's descriptions.

ST-Metric sized special trailer service tires will be branded with their load range (Load Range D or LRD) on their sidewalls and list their appropriate load range letter in their descriptions as ST205/75R15 LRD.

ST-Metric Trailer Service Tires

Load ----- Ply
Range---- Rating - Markings - Max Load Pressure
B-------- 4 -------- B -- ---- 35 psi (240 kPa)
C-------- 6 -------- C ------ 50 psi (350 kPa)
D-------- 8 -------- D ------ 65 psi (450 kPa)
E-------- 10-------- E -- ----- 80 psi (550 kPa)

==================
Note that in US and Canada, it is quite common to find only the old "ply rating" instead of Load Range in tire catalogs. Again, thanks to Brian B-P to remind me I'm a little old fashion

[The Minimalist]

Fuel mileage is another consideration. Radials do better in this respect.

Anyone out there changed from bias to radial and compared mileage? How much better was it?

Clif

[honda03842]

I've never measured the difference between tire types but high tire pressure do help mileage. I run my tires 6-13 pounds higher (13 in the rear and 6 in the front) than Honda's normal pressures when towing unless I am on a gravel road for extended periods.

[LukeP]

Earlier this summer I replaced some old bias ply tires with ST Radials. Not a fair comparison unfortunately, as the old tires were indeed very old - I replaced with Maxxis M8008 ST radials. That said, the old bias ply's were quite squirrely, the new radials are solid.

I did a bunch of reading on some trailer and boat forums too, for recommendations of bias v. radial and also brands. Seems like there are love/hate relationships with about every brand out there! The Maxxis had few bad reviews across the forums... not a very technical method to narrow down the options - but when everything else seems equal, it's a starting point! We've put less than 5000 miles on them, but I'd give them a big thumbs up so far.

[mcbrew]

Let me light a match... and throw some GAS on it!

Speaking of tires, let's remember something about tire pressure:

MAX means MAXIMUM.

MAX does NOT mean APPROPRIATE or CORRECT.

[lamimartin]

Is it OK to have a bias for properly inflated radials ?

[mcbrew]

Originally Posted by lamimartin

Is it OK to have a bias for properly inflated radials ?

Not sure what you are trying to say... But "properly inflated" is the operative term. There are a lot of folks here who believe that all tires should be inflated to the MAX sidewall pressure. Even though the companies who make the tires, and the companies who make the trailers tell them to do otherwise.

[lamimartin]

Originally Posted by mcbrew

Not sure what you are trying to say... But "properly inflated" is the operative term. There are a lot of folks here who believe that all tires should be inflated to the MAX sidewall pressure. Even though the companies who make the tires, and the companies who make the trailers tell them to do otherwise.

I should have said a BIAS for RADIALS...
(just kidding)

[floyd]

Radial trailer tires are the better choice for a travel trailer which will be used regularly. Carlisle now makes an excellent radial with improved UV and ozone protection as well as other improvements.
I have their former best tire on my Scamp and find them to yield great service and value.
However; if you are not going far or often and plan to change your tires by calendar, then you could use a lesser tire or even a bias-ply tire at half the price.
For what it's worth, here's my vote for best choice...

Tire Details - Discount Tire

[Borden]

ST175/80r13 is a radial trailer tire? These tires are made for the job at hand. Are the tires B, C, or D rated?

The r is for radial and ST is for trailer; our tires were over date "date stamp over 5 years" and car tires to boot so we upgraded to trailer C rated tires.
Our boler trailer came from factory with ST B rated tires new; C gives better lb rating and getting new tires anyway so went with C rating upgrade in r radial ST trailer tires.

This 17' uses ST205r14 C rated for 1760 lbs per tire or 1760X2=3520 lbs Max, with original equipment 3500 lb axle setting the new limit; B rated tires set limit too 3000 lbs; set by tires limit of 1500X2
(max psi on tire is 50 but recommended pressure on 17' units closet door of trailer is 32, too stiff or too soft is not good for safety)

The 13' units axle will set a limit on total as will tire choice, you only need to meet original equipment tire by law but can match trailer axle limit with the tires through tire rating to make it all it can be.

I am no expert but hope this helps

Originally Posted by Mr.Gauch

Hi everyone,

I have read most of the post regarding tires. I've got a newly acquired 1300 '70 boler that has been sitting for about ten years in a field. It has 155/80/r13 on it right now that are fairly weather cracked so i am in need of new tires. I will most likely go with the recommended ST175/80/r13 tires but no one has mentioned whether radial or bias is best. I'm thinking that bias ply tires would make the trailer pretty bouncy on the road going over bumps and such, but think that radials will make the suspension to stiff and produce the same results. Anyways, what are your suggestions/comments.

Thanks
Tyler

[DavidSo]

I can't think of one single reason to run bias tires on a trailer unless it is perhaps a 5th wheel. Bias tires develop more internal heat and so are more prone to blowout. They develop a flat spot when left sitting for extended periods. They wear out sooner, ride stiffer, and are more likely to cause vibration from poor balance. I thought this debate was 20 years in the grave . The one possible plus to bias tires is that they have stiffer sidewalls. They can resist the sideloads generated by 5th wheels in heavy jack knife. ST radials are supposed to handle that though. I wouldn't have a bias tire on anything. I'm old enough to remember how bad they were!

David