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Radial vs. Bias-Ply Tires

Posted in How To: Wheels Tires on May 1, 2011 Comment (0)
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Guy #1: "Dude, this guy in my gun club was telling me about his cousin's brother'snephew's roommate who could never get his bias-ply tires to take a balance. His Jeep went into death wobble and he lost control, hit a honey truck, and skidded through a plate glass window factory where he was decapitated."

Guy #2: "That's nothing. I heard from my ex-wife's Latin pool boy (whose salary I still pay, by the way), about this chick's Jeep with under-inflated radial tires. The front tires overheated, delaminated, and caused the Jeep to pole-vault over a busload of orphans and into an Acme TNT van. The ensuing explosion and fire contributed to global warming and directly resulted in the heat-stroke-related deaths of three polar bears."

Yes, truly the debate of radial versus bias-ply tires has had its various opponents and proponents over the years. Are the sidewalls of radial tires no better than paper or cardboard on the trails? Does a puppy die every time you mount a bias-ply tire on anything but a tractor? Who can really say for sure. But here's the Jp staff's take on the subject.

Size and price are two areas where bias-ply tires seem to have an advantage. Manufacturing costs and complexity increase as radial tires get larger, so you'll see more sizes and comparatively lower-prices in bias-ply tires larger than 37 inches.

Hardcore Hazel
I'm a realist. I don't expect my tax accountant to wash my car for me. That's not what I pay her to do. So why should I expect a glass-smooth street ride out of a gnarly set of off-road tires? I bought 'em to work really well in the dirt and to survive in the rocks. Conversely, I'd never pull the Michelin street radials off my wife's SUV and mount 'em on my flattie before heading to Johnson Valley. Unfortunately, some don't see things in the same shades of black and white as I do.

I like bias-ply tires. I don't care that they flat-spot after sitting overnight or that they may wear a bit unevenly. It's okay to me that if I do take the effort to have them balanced it may take as much as a pound or more of wheel weights per-tire to get the job done. Their hammer-tough carcass and brutal traction is all I ask in return. Historically, bias tires haven't been known for their long street life. I did put over 20,000 miles on a set of Swamper Boggers and still had almost half the left on them when I took them off. I consider that a fluke, though. It must've been the Perfect Storm of tire survival rolled into one absurdly remarkable scenario. Lately I've been running a set of small Swamper LTB tires on a Wrangler and their fast and uneven tread wear has restored my faith in the world order. Bias tires are largely old-school tires. Not a lot of new technology and effort seems to be lavished upon their design and manufacturing, but they are as tough and unsophisticated as a Boston dock worker.

Chicks prefer radials! There was an identical Jeep parked right next to this minus a set of bias tires, but the girls refused to climb onto "those icky bias-ply tires." No, really. We wouldn't make that up!

Radial tires, on the other hand, seem to offer the best of both worlds nowadays. In the past if you ran a radial tire you could expect smooth on-road manners (for the most part), but you also expected the sidewalls to be ridiculously susceptible to puncture and tearing on the trail. That's not exactly so anymore. Tire manufacturers are developing tighter sidewall weaves and have in some cases introduced bulletproof materials like Kevlar to bolster a radial's survivability. The end result is a tire that is manufactured to tight tolerances (meaning it's actually round instead of lumpy and oval), has consistent material distribution through the carcass (meaning it's balanced and requires less weight on the rims), and wears longer without giving up traction (meaning the materials in the rubber blends are more advanced). I think ten years ago I would've clearly chosen bias-ply tires for their crazy off-road attributes, but today the radials are just too good. As long as they're available in the size I want to run, make mine a radial.

Trasborg Goes Backwards
I've basically gone the exact opposite way as Hazel. There really isn't any room for argument about the rounded vs. square tread profile. Nor is there anyone in his right mind who would argue more miles from a comparable radial, and there is a small army of bias-ply people who don't even balance the tires sighting, "Even if you can get enough weight on it, you'll be out of balance again tomorrow anyway." Ten years ago, I'd have (and did) go for a radial every time. Bias-ply wasn't on my radar because they rode like crap and didn't last that long. Certainly I couldn't justify the loss of mileage against the price difference.

Manufacturing consistency and carcass stability is one of the advantages a radial tire has over its bias-ply counterpart. While both tires offer brutal strength and great traction off-road, note the nice, flat tread surface of the radial tire (left) versus the crowned, bulged surface of the bias tire (right).

Today I have a different point of view. While it is true that the manufacturers of radial tires are beefing up the sidewalls and designing treads that are infinitely more usable both on- and off-road, the sizes that I want to run just aren't available. Once they finally become available (two or three years after the tire's introduction), I normally don't care anymore because the next big thing is out. I don't want a 37-inch tire that fits a 20-inch rim. I love 40-inch tires, but once I see it is built for a 22-inch rim, I turn back to the bias-ply camp once again. When did a 33- or 35-inch tire on a 15-inch rim go the way of tailfins and Jeep pickup trucks? And don't give me any of that, "Oh, well the brakes are getting bigger necessitating bigger rims" junk, either. We were being forced away from our 15-inch rims long before the OE manufacturers were providing our vehicles with brakes that wouldn't work with them from the factory.

The other thing that I've seen change is the price differential between radials and bias-ply tires. Perhaps it is due to bias-ply tire design and construction not really changing over the years. Maybe all the whiz-bang design features, materials, and construction techniques that contribute to the durability and roundness of today's radials have really pushed the price higher. Maybe it is just the goofy sizes of radial tires I always see, but it seems to me like the bias-ply flavor of a given size will knock some coin off the buy-in price. But it seems that the price gap between radials and bias-ply tires has grown over the last ten years. The way I treat tires, I am probably never going to come near the manufacturer's mileage estimate anyway-so that facet of the argument is a wash for me most of the time. One caveat to this whole thing is that due to the flat-spotting and general lack of roundness, I'd never put bias-ply tires on a Jeep with a factory coil-sprung suspension. Control arm bushings and track bar bushings and ends wear too quickly as it is with larger-than-stock round tires. Oval or unbalanced tires will only accelerate that and you will have to replace track bars, tie-rod ends, and other associated parts with even more frequency.

Planning on making long road trips to and from the trail or simply relying on your Jeep to serve daily-driving chores? Your choice should be radial all day long. Bias-ply tires can have acceptable road manners, but it's the exception, not the norm. You'll generally get a smoother ride and longer tread life out of a radial.

Cappa's Tire Store
Bias-ply tires hurt overall performance, they typically don't roll round, they wear out quickly, they're noisy on the road, and they get flat spots when parked overnight. The main reason people opt for bias-ply tires on Jeeps is because of the increased sidewall strength, although the gap in sidewall strength between bias-ply and quality radial tires has closed in the last decade. A few of today's high-end radial tires are nearly as durable as a bias-ply. Plus they provide more stable traction on- and off-road, roll rounder, increase fuel mileage, and last longer. The decision is really simple: Most Jeeps should be rolling on modern radial tires. However, my next project Jeep is gonna have bias-ply tires. So why would I do that? Like anything else, it comes down to application. My next Jeep will spend most of its time off-road and there is a particular bias-ply tire that has tread features that work well where I plan to take it. If you're purchasing bias-ply tires, you should be doing so because their tread fits your specific off-road needs.

I don't balance my tires regardless of whether they are radials or not. I used to mount and balance 4x4 tires for a living, and like Trasborg said, a bias-ply may be balanced one day, and not the very next, even if it only sat in a parking lot. Large-diameter radial tires are almost as bad. The second you take them off-road and spin them in the dirt and mud, they likely need to be rebalanced again anyway. I just don't waste my time, money, or effort doing so.

Not all radial tires are equal. Some radials are more round and balanced than others. And as Christian said, the sidewall structures of the premium brands are quite an improvement over no-name brand radials. A low-cost, nobody-brand MT typically won't perform as well as a better engineered and tested name-brand product. With a tire, you're not paying for the name, you're paying for advanced tire tread compounds and carcass technology. And with a bias-ply, you're dealing with a technology that hasn't really changed all that much in over 100 years.

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