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Radials vs. Non.

Discussion in 'The Garage' started by motosaint, Jul 12, 2007.

  1. motosaint

    motosaint LTLYLTL!

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    I asked this question in the Gadget area, but I think it's more appropriate I ask here...

    I need to replace the tires on my '99 Katana 600. The owners manual says put radials on it. They recommend a crappy Michellin model. Which I won't do. However, the previous owner of the bike put non-radials on the bike.

    My questions is: are radials worthwhile? What's their pros?

    I ask since if I replace my tires with radials, then I have to replace both front and rear. Don't want to mix radial with non-radial correct? Though much of my riding is commuting on the freeway/city, I do some pretty fun single-day weekend rides and planning a trip through the Pacific Northwest in October.

    Thanks!
    #1
  2. Bigger Al

    Bigger Al Still a stupid tire guy Supporter

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    You'll get the most out of the bike by using the radials that it was designed to run. Don't mix radial and bias-ply tires, as funny handling quirks are bound to appear. The radial tire was designed to flex more as it goes down the road, providing a more stable and consistant contact patch. That could prove to be an asset, as you're bound to run into some wet conditions in the PNW that time of year. It's also lighter, and when run at the proper pressures should outlast the bias-ply equivalent.
    Go to www.americanmototire.com . You'll find some pretty good prices there.
    According to Michelin's site your bike should have a 120/70ZR-17 on the front, and a 150/70ZR-17 on the rear. Double check your owner's manual to see if that's right.
    A quick look through the American Moto site tells me that you'll expect to pay roughtly the same amount for any brand that you choose, which is to say $100 (give or take) for a front, and $120 (give or take) for a rear. I don't know what their shipping policies are, but it's worth a look.
    #2
  3. Aurelius

    Aurelius Long timer

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    Bias ply tires have a stiffer carcass than radials, resulting in a smaller contact patch. They also tend to weigh more. I've also been told by "people who know" that the internal construction of a bias ply causes more heat buildup, leading to decreased tire life. Since your rims were designed for radial tires, which have a different cross-sectional profile than bias ply tires, fitting them with anything other than radials may even pose a safety hazard.
    #3
  4. spanker

    spanker Lake City, FL

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    The Beemer F650 GS has a factory radial on the rear and bias-ply on the front. Don't ask me! I don't get it either but BMW is very specific on what you can and cannot put on this bike as evidenced by a sticker on the swingarm stating so. If anyone can enlighten me on what the hell BMW was thinking, do tell.
    #4
  5. dakarboy

    dakarboy ugly and stupid

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    kinda orangish

    i think in the context of a underpowered overweight 650 the tire mix is not as critical as on say a hayabusa?

    but still, if beemer does it they must have gone to the tire manufacturer and gave them clearly defined guide lines? beemer is the only one i know of that also has a approved tire list as well sooo.......

    i would not mix and match tires though, if it could be avoided that is.
    #5
  6. motosaint

    motosaint LTLYLTL!

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    I ended up buying the Metzler Roadtec Z6. I was told on numerous ocassions by different people, that the tire store I went to was run by 'tire geniuses'. The staff at the store told me that as long as I'm not doing over 80mph (Hwy) and not doing hard cornering above 50mph (I don't), that I should be okay.... For now. They too mentioned that cornering with two different sets of tires can make the bike handle funny. For now, I really don't corner very hard. Yet!

    They too recommended that I go radial for both and within a month, I will. I hate replacing the rear since it only has about 2000 miles on it. It's an Avon bias-based tire. I bought the bike used and was surprised that the owner was such a cheap-ass with such a nice looking bike. Though, the original owner does own his own house :puke1 And in the San Francisco Bay Area, that's impressive...

    What I really like about the shop I went to was that they educated me on the pros/cons and the "why's" on tire selection. They pretty much backed up my research. They originally tried to sell me Michellins or Bridgestones, which I think suck, and I don't know why. Cheaper? But I guess they got the vibe that I wanted the Metzler, we went with that and they gave me a great price.

    If you're ever in San Francisco, check out KC Engineering on Harrison, between 2nd and 3rd Streets. I was very happy with the pricing and especially, the service. I was in/out in 30 minutes AND they were busy too!
    #6
  7. Gonzodog

    Gonzodog Been here awhile

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    Here's some stuff I learned while working in tire engineering at a major US manufacturer.

    Bias ply tires have the cords running from bead to bead at about 40 to 60 degrees.

    Radials have one or sometimes two body plies (textile layers) that run from bead to bead at about 0 degrees + have usually two or three textile belts (nylon, aramid, or stranded steel wire) under the tread area (only) laid up at an angle of 60 to 75 degrees (from the circumferential axis).

    Because of this lay-up geometry, radials provide more uniform tire footprint pressure. It is inherrent in the geometry. So, they squirm less as the tire rolls through the footprint.

    Getting the road pressure of the tire footprint to be uniform as the tire rolls through the footprint is essential to road holding, traction, and maximizing tread durability/mileage.

    By way of comparison, passenger car tires generally have softer sidewalls so the uniform pressure distribution of the radial footprint is much more pronounced as compared to that of a passenger car bias ply tire. That makes the two VERY different for handling, tread wear, and turn-in responsiveness/cornering force.

    But, motorcycle tires need to have stiffer sidewalls by the means of either biasing the textile layup angle or by adding more rubber thickness in the sidewall area. (Wobbly motorcycle tires just arent popular!)

    Motorcycles don't handle well at highway speeds with soft sidewall tires so because of the sidewall stiffening added to the M/C tire radials the difference between radials and bias on M/C tires is less pronounced.

    Even so, I would expect radials in general to offer better traction and tread wear than bias ply tires.

    Lastly, radials should be thinner in cross section so they should build and hold less heat (since rubber is essentially a heat insulator) and be more durable at high speeds.
    #7
  8. dwayne

    dwayne Silly Adventurer Supporter

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    On my Concours I have mixed Bias and Radials. I have run radials on a bike "designed" for bias. I have had better results (in handleing in ALL conditions, and milage) from both combinations than the stock tires.

    Buy the right sizes, load ranges, speed ranges, and take it easy for the first bit 'till you understand the changes.

    Read the tire manufactures fitment charts, and other technical data; if you do that you will be better informed than 90% of bike shop tire wizards, and other self informed experts here. Including myself.

    I am a fan of Avon AND Metzler tires, and just because the tire is bias, that dosen't mean it's a bad tire.
    #8
  9. motosaint

    motosaint LTLYLTL!

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    After about 100 miles, the front Metzler is doing very well. It seems to have softened up a bit and rides VERY nice. A couple of weeks and I'll get the rear to match.
    #9