• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

120/80-18 on a GS1000?

  • Thread starter Thread starter atvpyrofreak
  • Start date Start date
A

atvpyrofreak

Guest
So, I really need new tires and I've decided on Avon Roadriders. I'm just having some issues with what size to go with. I've searched around and found lots of info, but I'm still unsure.

I have 19" and 18" rims front and rear (stock spokes). Im planning on using a 100/90-19 up front, as thats what most seam to recommend (and thats also currently whats on my bike). The rear is a different story. Currently I have a 5.2/18 on the rear which I know is on the large side. I see recommendations for 110/90's, 120/90's, and 130/80's, but I haven't seen anyone with 120/80-18's. Does anyone see any problems with this size? It should be about the same width as the 90, but about an inch shorter, right?

My problem is that im only about 5'6"-5'7". After sliding the forks up a bit and cutting my seat down a bit, I can ALMOST flat foot this bike, and I really think with a little shorter tire I will be able to. I know my RPM's will run a tad higher, but I'm not really all that concerned about that. I just want to know if there will be any mounting or performance issues.
 
A smig less cornering clearance, and higher rpm for any given speed. If you are okay with that, go for it!:)
 
atvpyrofreak said:
So, I really need new tires and I've decided on Avon Roadriders. I'm just having some issues with what size to go with. I've searched around and found lots of info, but I'm still unsure.

I have 19" and 18" rims front and rear (stock spokes). Im planning on using a 100/90-19 up front, as thats what most seam to recommend (and thats also currently whats on my bike). The rear is a different story. Currently I have a 5.2/18 on the rear which I know is on the large side. I see recommendations for 110/90's, 120/90's, and 130/80's, but I haven't seen anyone with 120/80-18's. Does anyone see any problems with this size? It should be about the same width as the 90, but about an inch shorter, right?

My problem is that im only about 5'6"-5'7". After sliding the forks up a bit and cutting my seat down a bit, I can ALMOST flat foot this bike, and I really think with a little shorter tire I will be able to. I know my RPM's will run a tad higher, but I'm not really all that concerned about that. I just want to know if there will be any mounting or performance issues.
Click to expand...

Lowering the tires is a bad way to lower a bike, stay with 120/90 or 130/90, the profile is important. How wide is your rear rim?

One of my 1000s has 2/12" wheels, the older one has spoke wheels and the rear is 1/4" or so narrower, I run 130/90 and 120/90 respectively.

Road riders are great tires.

Any bike I can flat foot is too small, that's what tiptoes are for. :-)
 
tkent02 said:
Lowering the tires is a bad way to lower a bike, stay with 120/90 or 130/90, the profile is important. How wide is your rear rim?
Click to expand...

Its a 78 GS1000C, and I'm pretty sure its the standard 2.15 width. I measured the outside width and its just a tad over 2.5.

Thats kinda what I was wondering, if by shortening the sidewall, if it would flatten out to tread or something like that. Its not a huge deal that I can flat foot it, but i just thought it would be nice if it didn't affect performance. I think it might also help once I get my rearsets built so my legs can go strait down from the seat, instead of having to pull them back behind the pegs.
 
I can not flat foot my 850. It's never been a problem
 
atvpyrofreak said:
Thats kinda what I was wondering, if by shortening the sidewall, if it would flatten out to tread or something like that.
Click to expand...
by installing a lower profile tyre (120/80 vs 120/90) you re likely to have the threaded surface curve more not less as the sidewall is shorter
120/80 ideally calls for bit wider rim than the 120/90

the overall difference in height between the two would be just under an inch, hence you d be lowering the rear end by 1/2 inch
 
Thanks guys, as always, the GSR's have pulled through with its wealth of knowledge. I think I'll just stick with with the 120/90.
 
Last edited:
atvpyrofreak said:
Thanks guys, as always, the GSR's have pulled with its wealth of knowledge. I think I'll just stick with with the 120/90.
Click to expand...

That's what I'm running. When I got my 78 GS1000, it had 130/80 on the rear. The tire was pinched and it didn't help the handling one bit. When I installed a 120/90, it was a huge improvement.
 
You must log in or register to reply here.
Back
Top