Tires Armadillo tire - just noticed something...

Discussion in 'Bicycle Repair' started by Mary, Mar 28, 2009.

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  1. Mary

    Mary Guest

    I am making a rack to hang a travel bag on the back of my bike. I just noticed the following on the sidewall of the tire: "Rotation" with an arrow.

    Has anyone else noticed this? I assume it is like a radial tires on cars. The tire is meant to rotate in one direction only.


  2. It has to do with thread design and water dispersion it has to rotate a certain way or your not getting maximum performance. Now as long as staying inflated I wouldn't think it would make much of a difference.
    But I do remember a tire I had with a rather thin side wall something like if you install it the wrong way the side wall can actually tear up but don't quote me.
    Last edited by a moderator: Mar 28, 2009
  3. loquin

    loquin Active Member

    With bike tires, you don't need to worry about water dispersion at all. At 40-50 psi, you would need to be hitting 80 MPH + before you could hydroplane on a slick.
  4. fetor56

    fetor56 Guest

    Most tyres don't have the rotational arrow meaning to me u can put them any way u want,but the ones that do it's better to follow the directions.
    If i installed a tyre with the rotational arrow incorrect i'de force myself to take it off & start again :dunce:.....thereafter check FIRST.
  5. Mary

    Mary Guest

    I agree with you. A local bike shop installed the tire for me and I didn't notice the directional arrow until much later. On Monday, I called Specialized and spoke to the tech dept. and the guy told me the same thing. He said it was important for traction. I figured with a motor assisted bike, I had better bite the bullet and take the tire off along with the motor and do it right. :sweatdrop:

    Forgot to mention: the directional arrow is pointed the wrong way.
    Last edited by a moderator: Apr 1, 2009
  6. vegaspaddy

    vegaspaddy Member

    wow you actually talked to someone in a tech dept that actually knows the right answer for a change.

    Since most of us are running some sort of mtb tire the good tires will have a directional arrow, it is also not unusual to find a good set with completely different threads,one designed for the back and one for the front, so yes it has to do with traction mostly coming into its own in off road preformance.
  7. Easy Rider

    Easy Rider Guest

    You picked a great all around tire Mary. I have a pair of Armadillos with Specialized thornproof tubes on one of my bike and have taken it on some rough terrain. The real test was when I took it on a 60+ mile dirt trail in the Mojave Dessert with 100+ degree weather. By the time I got back on the road, both tires were completely covered with thorns (at least 1000 thorns) I pulled everyone of them out and to this day the tires still hold air.
    BTW, the way you can tell if you have the tires on correctly is you stand behind the bike, The Vs will point upwards. My gut feeling is if they have directional tire arrows, there has to be a good reason why the manufactor wants us to install them that way.
    Last edited by a moderator: May 14, 2009
  8. loquin

    loquin Active Member

    There may be a reason to have the direction of the tread specified, but, you can be positive, with a bicycle tire, that it's not for water dispersion.

    Because auto tires have tread - in fact, NEED tread, so as to help with hydroplaning, bicycle tire makers seem to feel the need to include tread on their tires, too, as a comfort factor for buyers. There's no reason for tread on road tires, but, the marketing blurbs will say they're there to 'channel water.'

    At 50 psi inflation pressure, a smooth, treadless tire can't hydroplane 'till you hit nearly 70 MPH!

    The actual formula to calculate the potential speed that a hydroplane condition could exist is:

    Speed (in MPH) = 9.72 X the square root of the tire pressure (in psi.)

    The higher the air pressure in the tire, the higher the minimum potential hydroplane speed. Note that the only variable involved in this calculation is the air pressure...

    If you wanted to rearrange the formula to see what the minimum tire pressure would need to be, if your maximum speed was, let's say, 35mph, it works out to 13 psi.
    Last edited: May 17, 2009
  9. bamabikeguy

    bamabikeguy Active Member

    Learned sumpthin' yesterday.

    A customer brought his wife's bike over, (odd thing happened, the punctureproof tube had failed at the valve, "popped off"), when he put the wheel on, he goofed up the axle washer setting I had, and the brakes (and the axle angle...)

    Anyway, when he went to Wal-Mart to get the slime punctureproof tube, he asked the guy how much pressure they put in tires.

    The guy told Glenn that the WallyWorld compressors are set at "42 psi", and "manufacturer specs" don't matter (lawn mowers or bikes or back in the auto repair shop) 42 is what you get.

    Me? I always stay under specification, and never exceed 35 on the cheap tires that specify "40". (They fail at the bead when they hit a pothole if they have too much air).
  10. azbill

    azbill Active Member

    I got a set of armadillo crossroads for my b-day :)
    (front from azvinnie & my daughter, rear from the girls :cool2:))
    the sidewall says between 35-80psi
    at 40, they seemed a little soft
    bumped up to 50, and they feel much better
    what psi are other riders using ???
  11. bluegoatwoods

    bluegoatwoods Well-Known Member

    Most of the cheap tires I buy say "40-60".

    I mostly air them up to 40 and refill when they get down to the low 30s.

    Going just a bit off-topic; I wouldn't mind buying better tires that I could run at higher pressure without worrying. I've even done so, though it's been years.
    But I was disappointed to find that the sidewalls crack and break up just as quickly as with cheapos. And I clean and armor-all my tires pretty regularly. Sometimes I wonder if I shouldn't do it more. But I'm reluctant to feel that I MUST do it every third day or so.

    Still, it would have some advantages. Armor All not only protects vinyl, rubber,etc., but it's also very good at fighting rust. Fasteners and other small hardware benefit a lot from it.
  12. HoughMade

    HoughMade Guest

    No offense to any WalMart employees out there....I shop there frequently, but just because a WalMart employ said "42 psi is it"....doesn't mean squat to me. Actually, what it means to me is that I will check every tire I have installed there on anything.

    A lawn mower at 42 psi? More like 10 to 20 psi in many cases. An ATV? Under 10 psi. My car or van- max is 35 psi...I would be PO'd when the center of my tread wore out with 42 psi.

    Lastly, I hardly believe there is a Walmart wide policy to ignore tire pressure markings on tires. One guy, one place.

    I find that with road-going vehicle, the highest appropriate psi approved by the manufacturer is a good place to start. Adjust as necessary for ride and handling charateristics, but always within the range recommended.
    Last edited by a moderator: Dec 15, 2015
  13. Easy Rider

    Easy Rider Guest

    Bill, I usually set my at 55-60psi. 80psi seems like its too hard and might pop the tire when they heats up. I've had an issues once with another tire when I inflated it too much. It bubbled up on the side wall and pop.
  14. darwin

    darwin Well-Known Member

    My tires are kendas and they say 65 psi max and I run them at that pressure and it seems to be a nice ride at that pressure, plus with a friction setup I get better traction with the roller at max psi.
  15. azbill

    azbill Active Member

    these tires (armadillo crossroads) rock !!! :)

    just an update :)
    bumped my air up to 50psi...feels very solid now :)
    approx 150miles on them now...the little 'tips' haven't even wore yet :)
    I don't even swerve around debris anymore as I am confident the combo of these tires and my bell super thick slime filled tubes will handle it :cool2:
    I really like the looks too :)

    ps...I blanked out my engine so this pic would stay in the tire forum where it belongs

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    Last edited: Jun 2, 2009
  16. robin bird

    robin bird Member

    I have a set of Armidillo crossroads on my bike and find they are not as good on the trails as they do not bite into the gravel as well as my Maxxis tires do--but we have puncture vine here in Oliver B.C. and when you run over it they stay inflated !At first my friend pointed out that the bike shop had installed the front tire with the wrong rotational direction.
  17. I am no tire expert but I would think part of the direction on the tire might be to funnel the water away from you and has nothing to do with hydroplaining. I am runnin the extra thick green gubber filled tubes and the "comfort" bell 26" from Wal-Mart. The tire is kevlar lined and rated at 65 lbs pressure that's what I have in them. I know I have had over 300 lbs load on these things no problem (I weigh 250). They felt a little squirelly compared to the wider ones that came on my mountain bike but they bank well and I really like them now that I am used to them.

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  18. seanhan

    seanhan Member


    Run Surfas Drifters at about 55 psi
    Awesome tires, would buy them again ...
  19. Stoltzee

    Stoltzee Member

    Directional tyres usually have a chevron or arrow pattern in the tread and are designed to work in only one direction of rotation.

    Directional tyres disperse water that builds up in front of the tyre more effectively, reduce road noise, and improve directional stability.

    They must rotate in the right direction and this will be clearly marked on the sidewall of the tyre.

    If a directional tyre is fitted the wrong way round, the tyre won't be dangerous, but you won't gain any of the benefits of it's design.

    Incorrect fitting of both asymmetric and directional tyres is a reason for MOT failure.

    (Ministry of Transport) Test

    Standing behind your bike the arrow/chevron points forward.