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?
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.
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.
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?
I understand where you're coming from however the 180/55 is actually smaller in diameter than the 170/60.
Originally Posted by Roger 04 RT
To answer the OP's question, I suspect you have a 5" wheel width. If yes, I'd stick with the 170.
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?
Originally Posted by EMSimon
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.
Originally Posted by bikerfish1100
Nevertheless, I do appreciate the reply.
no conclusion jumping, other than to question if you were considering keeping the wrong tire size.
Originally Posted by Jade
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.
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.
Alrighty then. In my experience...
Originally Posted by Jade
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.