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Old 08-22-2008, 08:38 PM   #1
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Bias versus Radial

On Sunday, I get five new ST205 75 R15 from Goodyear.
They are Marathons.

But I have seen some posts about radial tires and some posts about bias ply tires.

What exactly is the difference, and should I have specified on or the other, when I enquired at Goodyear, or should they have asked me??
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Old 08-22-2008, 08:49 PM   #2
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As far as I know, the Marathon is only available as a radial. I personally think the bias would only be good on a trailer that never gets much speed (like over 45), such as a cargo trailer for around town. I personally don't think what a Bias is designed for fits the needs for a travel trailer.

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Old 08-22-2008, 08:52 PM   #3
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From: http://www.discounttire.com/dtcs/inf...ionAnxiety.dos


RADIAL VS. BIAS PLY
One old wives' tale has it that you should never put radial tires on a trailer. The sidewalls on radials, the tale goes, are too soft, allowing the trailer to squirm all over the road. Conventional bias ply tires are the way to go. . . or are they?

While radials were frowned upon at one time, today there is wide-spread acceptance of these tires. Which should you use? The decision hinges on your towing style, according to Ray Evans, executive vice president for engineering, marketing and sales of Titan Tire Corp. in Mogadore, Ohio. "While it is true that a bias-ply tire can provide more side-to-side stability than a radial, a bias ply also runs hotter than a radial," said Evans. "If you are pulling a
heavy load, and need an extra measure of stability, use a bias ply."
"On the other hand, if you do a lot of long-distance towing with a relatively light load at high speeds, the radial design may be better for you because it stays cooler than a bias ply," he said. The cooler the tire stays, the less it will fatigue.
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Old 08-22-2008, 10:12 PM   #4
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Well, from what I've read and know about tires, bias ply are actually the best tires for any trailer. Bias ply are significantly more stable side to side and are much less prone to sidewall damage and blowouts. One problem with any trailer towing is that the trailer tires get accidentally curbed. Bias ply have much stronger sidewalls and resist damage, for that reason. Yes, they do run hotter because of the thicker sidewalls and they are not as fuel efficient as radials. The higher heat is really meaningless because the design and materials of the tire are made for this.
What it comes down to is: do you want a stronger more stable tire or a more fuel efficient tire? It's really up to the individual so there is no "right" answer. It's kind of a hard decision to make, it's too bad you can't get all the attributes in one type of tire.
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Old 08-23-2008, 07:23 AM   #5
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Hematite

I understand, and agree with what your saying. Just curious as to what type tires you will, or have bought for your Sunline radial or bias ?

Also last time i checked Bias tires were cheaper than the same size/rating radial tire. That being the case, I'm wundering why "ALL" the camper manufactures as cheap as they are, arn't putting the cheaper Bias tires on their new campers ? I do from time to time see bias tires on some new campers, but most I've noticed including our sunlines have radials from the factory. not disagreeing just curious. Any thoughts ?

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Old 08-23-2008, 07:49 AM   #6
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I think the manufacturers put on the radials because they know the average customer isn't going to sit around and do 45 or 55 on the highway. They want to get where they're going because they're on a limited time schedule.

Also, when some of these chinese companies such as Mission offer such unbeatable prices, I'm sure it could compare or beat what a bias tire would cost.

Jon
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Old 08-23-2008, 10:47 AM   #7
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As far as I know, the speed limit rating is exactly the same for both bias and radial tires. I've never seen where they are rated differently. Frankly, for trailer use, with the heavier sidewalls I'd be more confident with bias ply than radials at any speed.

Why do manufacturers use radial ST tires? I'd be surprised if there is $1 in difference to a manufacturer whether they use radials or bias ply. They buy in volume so they get the price. Also it's a great advertising gimmick to say that the TT has radial tires because your tow vehicle has radial tires and radial tires are just better, right?......Maybe, maybe not.

As to what tires I will eventually use, I don't know for sure but as of now, I'm leaning towards bias ply. The concept of "gas saving" radials is sort of ridiculous when you're pulling a TT. I'm more interested in directional stability and tougher sidewalls.

And for those of you too young to remember bias ply tires on cars, I drove them at speeds well over 100mph for hours on end and NEVER had a tire failure and certainly never had a blowout. My wife and I both have had sidewall blowouts on radials and we never went over 65mph and never hit a curb and that with "quality" radials.
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Old 08-23-2008, 11:03 AM   #8
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Oh, and when myself and other folks, back in the '60's and '70's, were driving those stupid speeds on those inferior tires we didn't even have the benefit of speed rated tires, either! I guess we didn't know any better and we liked it that way!
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Old 08-23-2008, 11:52 AM   #9
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This will be an interesting thread, for some time to come .

I checked the bed for my truck, for the stabbed remains of my tire to see what I was running, as I don't want to change horses midstream .

My tires were Maxxis radials, that I will assume were original (I am second owner) due to the 2002 mfg date.

Can't wait to ask the Goodyear guys to tell me what the mfg dates are on my new tires.....
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Old 08-23-2008, 12:31 PM   #10
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Tires, gas mileage and safety.

If you want the maximum of all of these make sure they're properly inflated, whether radial or bias.

We're long range long interval campers and I'm absolutely paranoid about the tires, checking them every time I stop for unbalanced temperature and checking the air pressure regularly.

The best solution for safety is to drive slower. I see RVers continually driving faster than the tire's rating. As to concerns for mileage nothing beats slowing down. My wife is found of telling people I drive in the OPL - Old People's Lane.

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Old 08-23-2008, 03:03 PM   #11
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Definitely, monitor tire pressure regardless of the type. Underinflation is probably the #1 killer of tires. Driving faster than the rating has got to be up there as well.

There's absolutely no reason to go faster than the 65mph rating, yet I frequently see people towing TT's do just that. I blame the TT manufacturers. There should be a conspicuous decal to warn owners not to exceed 65mph. They put a decal on the rear of the unit warning about the 100 lb max load on the bumper, yet no tire speed warning decal?

You'd think people would use some sense and not travel at ridiculous speeds while towing but that doesn't seem to be the case!
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Old 08-23-2008, 05:29 PM   #12
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I personally have two reasons to go over 65. Most of the time I keep it about that (68 on the speedo, which is usually about 3 over anyway), but occasionally I'll hit 70 with it or a little higher.

1) Better gas mileage. With the 3.73 rear end (which I didn't have the choice on since it's used), if I keep it between 45 and 65, it constantly shifts in and out of 3rd, 4th, and OD. If it's at 68 to 70 (on the speedo), it stays in OD all the time and doesn't shift out until any slight grade. I've never calculated numbers, but I'm sure it's better when above 65.

2) Trans wear. The trans won't wear as much since it's not gear hunting. I especially had to keep this in mind while en route to the M&G because the trans kept making a noise when up-shifting. I don't know if the trans has ever been flushed, but I've got the materials waiting at home whenever I get there. It's only a problem that occurs when towing.

However, I have seen people, including one following me a couple weekends back (a PUP), and they passed me doing at least 80 in the hammer lane. Now that kind of driving is just plain foolish, even when not towing (Keep in mind though the SL here in MI is 70, not 65 or 55).

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Old 08-23-2008, 07:32 PM   #13
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Jon,
I won't use OD because it does encourage driving faster to stop the shifting and because OD is not a gear but a band and I don't want to stress the band. Another reason is that is much easier on the engine to keep ot spinning 2200-2500 rpms, while under load ( MUCH easier on all the bearings). Since this is also nicely into the torque band it's a lot easier for the engine to pull without shifting down. When you take your foot off the throttle when you're out of OD the vehicles start to slow down immediately, as well. There are a lot of advantages to not using OD and, so far, it's working for me.

Gas economy is probably lower with not using OD but it is less stressful on the drivetrain and on me.
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Old 08-23-2008, 09:30 PM   #14
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Overdrive

This is an interesting discusion. Our tow vehicle has a standard shift so there's none of the hunting and pecking for the right gear, allowing me to keep the engine in a good operating band.

My motorhome has an automatic and I use overdrive all the time. When I see a hill coming up I do drop it out of overdrive.

I do regularly have my transmission flushed, every 25,000 miles.

I never let it overheat, temperature is a transmision killer. I noticed when it rains the temperature never climbs so I rigged my windshield wiper to spray the transmission radiator activating from a dash switch. We're approaching 90,000 miles, without a problem, knock on wood.

The drag on a trailer doubles for 70 mph compared to 50. It's hard to imagine that mileage can be better at higher speeds.

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Old 08-24-2008, 09:05 AM   #15
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Norm,
Pretty clever idea about the winshield washer spraying on the transmission cooler. Nothing like a shot of cool water to bring temperatures down. If you use winter mix, with alchohol, it'll really bring temps down!

As to the tires, after reading the statement from Titan tire, it's pretty clear that they are recommending bias ply for heavily loaded situations. Travel Trailer tires are rather heavily loaded tires. When adding up the capacity, at max pressure, of the tires on my Sunline I see where they are just barely capable of the max GVWR with a small margin extra. I think that a situation like that really is a heavily loaded one.

The tire life in mileage is higher on radials. Another case of it's great on cars but not needed on a trailer. Only a very few people will ever wear out a bias ply on a trailer before the 6 year time period for replacement expires. In my situation, the tires will dry rot long before any kind of tread wear will occur.

Eman would be the perfect tester for a comparison of bias vs radial. Maybe he has used both and can comment. Hopefully, he will see this thread and give us some firsthand information, in that case.
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Old 08-24-2008, 09:25 AM   #16
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I have two cents on this subject...let me spend it here. First on tires. I will locate a Denman dealer ( http://www.denmantire.com/ ).when I'm ready to replace tires. I will be interested in what they have to say about bias vs. radial ply too. They supply bias to a broad range of users from heavy construction to farm trailers...and yes to campers as well who have found about Denman as a brand.

All our camping rigs are different in some way and as such we drive them differently based upon personal experience, opinions and schedules. My Dodge truck has a Cummins diesel engine with a power band that places it's maximum torque of 600 ft lbs right at 1600 RPM's. That occurs at about 56MPH with my 3:73 rear end. It is the way a diesel engine does it's work...lumbering along steadily at relatively low RPM and applying massive pulling power to it's load. All the big trucks in commercial service use diesels, as it is proven for heavy hauling with relative efficiency. My transmission does not hunt for a gear unless the terrain gets very hilly, and after a few hundred miles of interstate it seems happy in OD at 1600-1650 RPM's doing about 56-58 MPH. That's my chosen speed as my driving time is part of my enjoyment. I want to make it as stress free and controllable as I can make it....and I should mention safe too. I get 15+ MPG when towing this way too and that helps me since diesel has become the highest priced fuel.

In conclusion I feel it is worth some special effort when it comes time to buy trailer tires. The easiest to get and most recognizable brands are not necessarily the best option. Obviously opinions will range widely on such matters and ultimately you have to make a decision and put on something. Once you do please get the right air pressure in them, and for Gods sake don't be out there speeding the daylight out of them just to get to Grandma's an hour earlier. The best option to use for a towing rig is your HEAD..!

Safe Travels

Bob
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Old 08-24-2008, 11:22 AM   #17
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Tires

With my Goodyears on the tire I'm running at 75% of load capacity. On the motorhome I've upgraded from E rating to G rating to gain 2400 pounds of capacity, giving a 15-20 percent margin. The E types, Michelins, were forever blowing, even though within load and never being driven over 60 mph.

So far there have been no blowouts with G's while there were 5 with Michelins, a Michelin blowout is the loudest sound I've ever heard.

Norm Milliard
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Old 08-24-2008, 04:18 PM   #18
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Getting back to the bias vs radial, i have seen some pretty big "new" travel trailers, with bias tires on them from the factory. i gotta believe when they were delivered to the dealer someone who delivered them pulled them over 45 mph.

i too am old enough to remember when there were no radial tires, they were all bias, and they worked pretty well. That being said I just bought 4 new "Radial" tires for my sunline, right or wrong because, radials came, on it from the factory. I to check my air pressure before every trip. the 2 blow outs I have had were on 85-90 degree days, traveling (I 95), at 65 mph maybe a little over from time to time. Thats the problem when you have more truck and engine than you need for a given trailer, and you pull in drive not overdrive. I'm going to slow down with the new tires, to around 60-62 mph.

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Old 08-24-2008, 04:35 PM   #19
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We've used both bias and radial trailer tires on our popup and our 2K pound rated utility trailer at different times. Had no real issues with any of them, except the Carlyle branded tires. Best results with the Goodyear Marathon radials and the DURO bias tires. Currently have the Goodyears on the popup and DURO's on the utility trailer. I normally tow at a max of 60-65 mph unless I absolutely MUST go faster to safely pass or merge.

Since we've never towed a really heavy trailer (our popup has a max GVWR of 3000 pounds) and we're about to purchase a 2499, I've been researching the tire subject in case I need to replace the tires on the Sunline (if they're aged or showing heavy wear). Interesting subject with many points of view.

I have come to the conclusion that the radial tires we have on our popup right now are appropriate for the lighter weights encountered. But I do think that while there MAY be a small difference in the fuel mileage gained using radials, it likely offset by the frontal drag and heavier weights we'll see in the 2499.

People in our camping group with travel trailers seem to prefer the bias tires and without exception use the DURO brand. Those with lighter rigs are split between bias and radials... the radials are ALWAYS Goodyear Marathons.

There seems to be little price difference between bias and radials in the sizes we'll be looking at. Right now, I'm leaning towards using the 8 or 10-ply rated DURO bias tires if and when we need to buy new ones on the 2499.
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Old 12-19-2008, 04:18 PM   #20
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So many threads about tires, including one of my own, but I think this is a good place for this....

I found the information below at http://www.titantires.com/specifications.htm. I bolded a few items which are regularly discussed.

I am beginning to lean towards a bias ply Denman if I can find someone who can sell me a set in my area. Unfortunately it means purchasing a set of 5 instead of 4, and I will have two 'new' radial tires that will not be used.

After reading the various posts, it seems a pressure monitoring system is also a good investment. I heard my Mission tire blow, but I have read several posts where the failure was undetected resulting in significant trailer damage.


Later,
David


WHY SPECIAL TRAILER 'ST' TIRES?

Eastern Marine carries a full line of nylon bias ply trailer tires. 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.
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