Size front tire R 100 GS

**Lars** · #1 15 Aug 2006

Hi there,

I know the size of the front tire of my R 100 GS as being 120/90/90 - 21"

A tire dealer in Delhi told me that would be the same than 275.21

Is that true?

Regards

Lars

**AnteK** · #2 15 Aug 2006

Quote:

Originally Posted by Lars

Hi there,

I know the size of the front tire of my R 100 GS as being 120/90/90 - 21"

A tire dealer in Delhi told me that would be the same than 275.21

Is that true?

Regards

Lars

Well, 120/90/90-21 does not exists. You obviously mean
on 90/90-21, usual size of front wheel. That is equal as
3.50-21, and 2.75-21 is smaller dimension. I will not use
it. Am I right?

AnteK, XTZ 660

**javkap** · #3 16 Aug 2006

Hi
The 90/90 its closer to the 3.25 the 3.50 it’s a little bigger.
Try to find it in this order: 90/90 – 3.50 – 3.25 – 80/90 or in the worst case the 2.75
Good luck

Javier…
www.DakarMotos.com
Buenos Aires – Argentina

**motomech** · #4 17 Aug 2006

Quote:

Originally Posted by Lars

Hi there,

I know the size of the front tire of my R 100 GS as being 120/90/90 - 21"

A tire dealer in Delhi told me that would be the same than 275.21

Is that true?

Regards

Lars

The correct size is 100/100-21, but I have used both 90/90-21 and 3.00-21.
The point we are missing here are the tire ratings, for the GS, you need at least a 51R rating and you are not going to find that on a 2.75. Not to mention, you probably couldn't get it to mount tubeless because it's too skinny. Running a 2.75 on a GS is down right dangerious, so don't do it. Find the strongest 3.00-21 and run that. Even if it's not tubeless, you can run it that way. Only as a last resort, install a tube.