140/80-17 rear Desert on Transalp?

**Pedro Rocha** · #1 14 Sep 2005

Hello, I´m pondering fitting a rear Michelin Desert tyre on my Transalp to use on rocky tracks and general offroad in Morocco.

What´s making me a bit insecure is the size of it, the rear Desert´s closest size is 140/80-17 but my stock tyre is a 120/90-17. Is the difference between 120 and 140 too big?

Anyone got experience on this tyre with a 120 wheel?

**RichLees** · #2 15 Sep 2005

shouldn't be a problem with the rim - I've fitted them to 2.15 inch rims. might be tight to fit and need to be sure it clears the swingarm all round and doesn't hit mudguards etc.

**Ian Bradshaw** · #3 15 Sep 2005

Sorry that I can't say if this tyre will fit your bike, but maybe this will help:

Michelin's 140 width tyres are narrower than some other makes.

Michelin along with Pirelli use the ETRTO standard for specifying tyre width, this is the overall width including the tread.

Some other manufacturers use the ISO standard for specifying tyre width. This specifies the width of the sidewall.

So a 140/80 desert will be a similar size to an ISO (eg Trelleborg) 120/90 tyre.

At least with ETRTO you know what the overall width is (140mm) so you can measure if it should fit before buying one.

Ian

**Pedro Rocha** · #4 15 Sep 2005

Ian, do you know what kind of standard does Metzeler or Bridgestone use?

**Ian Bradshaw** · #5 15 Sep 2005

Sorry, I don't know about Metzeler, they do not seem to give this information on their website. They aren't however, members of ETRTO. I think this means they are likey to use ISO sidewall width measurements, but to be sure, if you have a correctly inflated Metzeler tyre on an appropriate rim then measure the sidewall width to check it's within a couple of millimetres of the designation on the tyre.

Bridgestone are members of ETRTO. Just measured the 90/90-21 on my bike; this seems to confirm they use overall width measurements (sidewall width 79mm, overall 92mm)

This page confirms Bridgestone use ETRTO markings: http://www.firestone.co.za/content.asp?id=96

Here's a list of ETRTO members:

http://www.etrto.org/members.html

<edit>: My mistake, Metzeler are indeed members of ETRTO - but this may not be a clue as to which width measurement they specify as Trelleborg are also ETRTO members, yet use ISO tyre width designations.

[This message has been edited by Ian Bradshaw (edited 15 September 2005).]