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Thread: R1150RT Tire Size question

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    R1150RT Tire Size question

    I'm replacing the Pilot Roads on my 2004 R1150RT. I note however that the factory size for the rear is 170/60 ZR17, but the previous owner was running a 180/55. Is anyone else using this size? Are there pros and cons of doing this?

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    no advantage in fitting a larger tire. usually done for 1 of 2 reasons: the "ok reason" is because that was what was available, or the price was stupid good. the "not ok reason" is someone believed the old racing adage that a larger tire was "faster". it ain't, at least not for your purposes.
    Ride Safe, Ride Lots

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    Registered User roger 04 rt's Avatar
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    6th gear is already too high for the 1150RT, meaning that the engine is turning only 6,250 RPM at 125 miles per hour. The peak horsepower isn't till about 7250. So it seems that a smaller tire in 6th gear might lead to a higher speed because you could get to higher engine RPMs.

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    handling will not be better with the fatter tire on an RT, unless the wheel is sized for it. even then, handling will not necessarily be better. that is what i was attending to in my response.
    Did the RT ever get the 5.5" wheel?
    Ride Safe, Ride Lots

  5. #5
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    Quote Originally Posted by Roger 04 RT View Post
    So it seems that a smaller tire in 6th gear might lead to a higher speed because you could get to higher engine RPMs.
    I understand where you're coming from however the 180/55 is actually smaller in diameter than the 170/60.

    To answer the OP's question, I suspect you have a 5" wheel width. If yes, I'd stick with the 170.

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    It may be very difficult to get the wheel on and off with the fat tire. I have a hard time with the 170. I have to loosen the exhaust muffler and move it out of the way. Even then it is a chore.

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    Quote Originally Posted by EMSimon View Post
    It may be very difficult to get the wheel on and off with the fat tire. I have a hard time with the 170. I have to loosen the exhaust muffler and move it out of the way. Even then it is a chore.
    Couldn't you just deflate the tire?

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    sure, you could deflate it. that would only leave the handling compormises to address.

    but that brings us to an underlying question of "why is it you are thinking of keeping the incorrect size tire on there?" just because the previous owner used the wrong size?
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    Quote Originally Posted by bikerfish1100 View Post
    sure, you could deflate it. that would only leave the handling compormises to address.

    but that brings us to an underlying question of "why is it you are thinking of keeping the incorrect size tire on there?" just because the previous owner used the wrong size?
    I think you sort of jumped to a conclusion. In my recent reply I was speaking to the poster who said he had to loosen his muffler to get the stock size tire off the bike. In my original post I was inquiring as to pros and cons. As it happens there is a post back a ways that discusses the use of a 180/55 on the rear. I was hoping for some fresh opinions. As far as why I am thinking anything, I'm mostly interested in knowing what others have actually experienced between the two tires, rather than speculation or theory.

    Nevertheless, I do appreciate the reply.

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    Quote Originally Posted by Jade View Post
    I think you sort of jumped to a conclusion. In my recent reply I was speaking to the poster who said he had to loosen his muffler to get the stock size tire off the bike. In my original post I was inquiring as to pros and cons. As it happens there is a post back a ways that discusses the use of a 180/55 on the rear. I was hoping for some fresh opinions. As far as why I am thinking anything, I'm mostly interested in knowing what others have actually experienced between the two tires, rather than speculation or theory.

    Nevertheless, I do appreciate the reply.
    no conclusion jumping, other than to question if you were considering keeping the wrong tire size.
    there have been multiple threads on this question at http://forums.pelicanparts.com/bmw-r...0s-tech-forum/ There, the ? was typically driven by the isssue of the R11S having run both the 5" and the 5.5", fitted with 170/60 and 185/70, respectively. Guys would ask your same question. The response always came back as "don't do it."
    do a search, you'll find something.
    good chance it's been asked/answered here as well.
    Ride Safe, Ride Lots

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    Deflating the tire on the modern low profile tires is not much help. The edge on the sidewall does hardly retreat when the tire is deflated.

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    Quote Originally Posted by Jade View Post
    ... I'm mostly interested in knowing what others have actually experienced between the two tires, rather than speculation or theory.
    Alrighty then. In my experience...

    Running a 180/55 on a 5" rim distorts the tire's carcass, and the tread surface, from their optimal design parameters. In this case, the edges of the the tire would be "pulled in" towards the centre of the rim and leave you with less contact patch at a given lean angle than you would have were you running a 170 on that same rim. I've tried it. That is what I saw. Will it kill you? Probably not.

    Hope that helps.

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