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quick tire question?

Discussion in 'Eastside' started by freezincold, Jul 20, 2005.

  1. Because of my ignorance I have this question..(from another thread but thougth it was interesting)

    I just thought, it brings up another point, the new(ish) pilot powers...they are speed rated to 169 I think it is...is this a better or not as good rating as the 149 plus rating other manufacturers use?

    when they say 149+, what speed does that encompass? to 300? to 400? or to 150mph constant speed for 1 hour or 5 days???

    anyone know how they rate these and exactly what the numbers mean?

    maybe this is a question for the vendors at the track.
     
  2. I guess it says >169 wich is read "more than 169"

    never mind.
     

  3. snake

    snake Paralized with excitement

    Let me know if you find out. I just put a power on my rear and I need to know how long I can run it over 170. 8)
     
  4. I thought that was what the z-ratings on tires were for, no?
     
  5. you would think so at first...but then if you put 2 and 2 together you see people at races who have tire failures. Granted they are pushing it very hard.

    Hers the catch...it is harder on tires to run at a high speed on one section of the tire than be going side to side through turns...wich spreads the heat a little and gives one section of the tire time to cool.

    You have to imagine motogp race tires are at least speed rated to the 149+ right? even they fail occasionally.

    Even at superbike level for example-I was told anyway at daytona the superbike class was not the daytona 200 this year...because the tires couldn't take the high speed on the same contact patch of the tire that the big banking provided...for the long race. They were fine for the shorter race. (600cc machines were the daytona 200 this year)

    Now if a person is holding 140 or so on the interstate.(by the way...I'm not actually saying I would do that but somehow I have seen tires that have done it for extended periods and they look all boogered up on the center...similar to how the edges of a tire look after a day at the track)..I would think, since this is a higher speed than a lot of tracks even offer and definately a more extended time spent at that speed AND MUCH more extended time on one section of the tire (the center) that this may be an issue....
    (could it be a good case for sticking to lower speeds? say it's not so.)

    Catch my drift now?

    Then we see how Michelin Pilot Powers are going away from giving 149+ speed rating and saying 169 or whatever. Maybe this is the limit of constant operation at a specific ambient temperature and on one section of the tire?

    It seems they could leave themselves open to lawsuit by saying 149+ and then having people going 250 or something for more than a few seconds. and then having a tire failure..how cool would that be...250 on ground...YIKES!

    I think in the past things have been kind of understood that most people don't drive extended periods over 120 or so and the people that went faster only did so for a few seconds and then slowed down...

    Technology has given us better chassis and suspensions now that make things quite safe at those speeds...if it wasn't for the pesky deer!
     
  6. Did I say interstate? I meant Bonneville....
    By the way, would anyone be interested in a ride down there for speed week?

    I think it is in Sept or the end of Aug.

    It is an amazing place... not even accessible during certain times of the year as it is a bog. It self-levels and dries every year to my understanding...giving us a nice area to play on!
     
  7. the rating is the letter - most sport bike tires are all Z rated which is far higher than any mortal can ride on the street - something like 180 mph for 4 straight hours or something absurd like that - buy any Z rated tire and you're good to go -

    Steve
     
  8. Hey Steve! cool to see you are back! Hope your whole trip went well..I stopped by your place with the bike the other day but you were not back yet...or noone was home or something.When will you be up for a ride?

    EXACTLY Z SPEED RATED = 149+

    Is 4 strait hours at 180 the standard they use to test tires?

    Where did you get that info? that is awesome!

    Muchos Gracias Senior!
     
  9. Z rated tires are 149mph+ but if there is a W or Y then the speed capability is more than the 149 like 168 to 186 Speed rating indicates the maximum speed a properly inflated tire will withstand for a time.
     
  10. Perferd

    Perferd Grade A Champion

    How is it possible to run at tire at 180mph for 4 straight hours?
     
  11. It is not...but like many things there has to be a built in safety factor.
    For example the breaking strength of 1/4 inch cable is something like 20000 lbs but the working strength is something like 5000 lbs.
    Z speed rating (149+) is to my knowledge the highest speed rating.

    the question is more how is the 149+ (Z ) speed rating acheived, what speeds are actually attainable AND sustainable and for how long.

    While I apreciate Steve's stepping up with an answer (180 for 4 hours) there are a lot of questions that go along with this.

    What temperature was the road (or more likely drum)
    what was the ambient temp?
    was the tire kept on the center using the same contact patch, or was it introduced to "turns"
    and most importantly...is that actually the way it is tested...he didn't seem so sure.

    I have seen a lot of people on the net who sounded more sure than Steve about a certain "fact"- only to find out the didn't know what they were talking about and giving false information.

    I'm not saying Steve doesn't know what he is saying...(if I believe anyone it would probly be Steve) I would like to know where that information was gleened from though...
     
  12. The testing is done in a laboratory setting, I'll check some more on this for ya.
     
  13. My comment on 180 for 4 hours was meant to be an example of not an absolute - the reality is that nobody on the street will wear out a Z rated tire under "normal" operating use - you'll need to replace thet tire when the tread gets to the point where it's not safe ( and believe me when I say I've seen riders in this group that are using tires that are well past their safety limit, but it's their choice. No tread left on the middle of the tire means it's time to throw them away - my point ( probably made poorly ) was that a Z rated tire from any mfr. will withstand anything you can throw at it and will require replacement when the tread is showing wear or most likely the tire is flatened out in the middle from constant high speed STRAIGHT riding. when the day comes you wear the sides out faster than the middle then you're an accomplished rider - I'd love to live that long and have friends that do need to replace their tires after a 1000 miles because they've scrubbed the sides so much their is little tread left on them -

    No need to worry about mfr's tire as long as you're buying the right tire for your bike Z rated and replace it when it's worn - it need not be a full street/sport tire it can be a middle priced tire like the Michelin Pilot Road and give you ample wear and still will be plenty sticky for most if not all riders on the road - if you feel you're so hot that you need the Pilot Race or Pilot Sport or a similar tire than go for it- but any tire is going to be better than most riders as long as you replace them when you should and not try and squeee the last mile out of them.

    My two cents and I admit I'm not tire expert - I've bought Dunlops. Pirelli's, Michelin and Bridgestone -some I like better than others but they are all great tires and will do far more than I'm capable of ever putting them through - so buy the tire you want or better yet buy the tire you can get the best price on as long as it's the correct tire for your bike - as in size and rating -

    Steve
     
  14. my point is, when the manufactures made the z (149+) rating...virtually no car or bike was capable of sustaining that speed.
    Now in some areas you can burn a full tank of gas at 140mph and not in a laboratory setting...hot roads with ambient temps of 100+...

    Then factor in the occasional burst to 160 or 180....

    I didn't say it was smart to do this...

    I think it would be nice to find out what procedure they do to come up with that rating.

    I like absolutes...kind of like how steel bellhousings are tested for drag racers...spin the flywheel to 10,000rpm and saw through it until it grenades...if the bellhousing contains it without shattering, it is approved.
     
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