BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

Anyone use a 120/60/17 on the front rather than the 120/70/17??

Any ill effects?

Just a thought...it might put your speedo out a little.

DJ

DJ Downunder wrote:Just a thought...it might put your speedo out a little.

DJ

Or in where it belongs maybe, since it comes "out" from the factory?

BoiseBeemer wrote:

DJ Downunder wrote:Just a thought...it might put your speedo out a little.

DJ

Or in where it belongs maybe, since it comes "out" from the factory?

Wouldn't the 60 make it worse ? The 60's shorter then the 70 isn't it ?

Airman wrote: Wouldn't the 60 make it worse ? The 60's shorter then the 70 isn't it ?

Ouch. Don't make my head spin. If the tire's shorter, wouldn't the bike travel a shorter distance for each revolution? Thereby making the clock a bit more pessimistic in relation to the sensor's... uh... sensing?

Too late. There goes my head.

speculation run amuck

I hope this helps. It's a calculator that I found online that will compare stock vs another tire size. From what I saw it will change the reading by 4%

http://pw1.netcom.com/~sgalaba/tiresize.htm

frankly I could care less about speedo error since my radar detector regulates my speed.

i'm more interested in fit and handling peculiarities if there would be any.

i would expect being bit a shorter the handling would be one thing that's noticeable, maybe not?

also thought it might be common fit for the vertically challenged.

Oh, Well in that case, you should be fine to mount that tire. The tire is the same width, just with shorter sidewalls. You would probably notice the bike sitting lower if it's next to another stock RR, but i doubt you would notice any real difference. Possibly a stiffer ride. If you're not worried about Spedo error, I'd say go for it, but let us know what you think as far as height/ride/handling.

The tire change will make the speedometer 9.6% faster than before. The rest is pretty much along what Lobo125 said........

What about a 180 rear? Not for show, but because they're much cheaper than the oddball 170. Are they too wide for the rim?

Doesnt the Rockster run a 180 rear? Possibly an R1100S wheel would do the job.

As for fitting a 180 to the rear, it can probably be done but ideally you need a 5.5" rear wheel, which the Rockster comes with. I think changing the profile of one tire and not the other (or even both) may affect the handling of the bike - could make it better, could make it worse, you may not even notice it.

On the R1150R you have to watch for possible interference of the sidewall with the arm at the front. I believe that some of the early Rocksters had a small shim, at the hub, to fractionally space the wheel out and provide suficient clearance.

The 180 tire will "hamper" the handling slightly......

Found this (older) thread via a search for this topic... I'm curious about the results of putting the different tire size on both front & rear from NHighCotton (or anyone else that has tried it). I was also considering putting the 120/60/17 on the front to help drop the bike a tad (only ~1/2" diff between 120/60 and 120/70 tires), as well as putting 160/60/17 on the rear in place of the 170/60/17 (providing only ~1/3" drop). However, both together would probably be enough to provide that little extra comfort level, along with the low seat, for my wife when she rides the 'R'. I asked swmototires.com about this, and they gave an emphatic DON'T DO IT without any reasons behind that response.

What are the opinions of the seasoned experts on this board?

The change in tires size were dealing with here is minimal.

How to read the tire markings.

170/60/16 = 170mm is the width, 60= the height of the sidewall is 60% of the width of the tread. 16= the rim size.
That being said, if you go with a lower profile I can't see where that would greatly affect handling. Metzler me880's have the same tread design and radius in 70 series or 60's. The tread angle is going to be the same and there should be no ill effects. I would use the same brand and style front and back.Hope that helps.

Thanks... I was of the same opinion (that it's not a big deal), so the response I got from swmototires.com was a bit of a surprise. Made it sound like the 'bike would explode if I tried to put different sized tires on it. They never did respond back when I asked "Why do you think it's a big deal?"

I'll just go for it. In the meantime, if anyone's already tried going to different (smaller) tire sizes (width & ratio, obviously not diameter) without changing the wheel, please post your experience.