07-07-2026, 07:21 AM
(This post was last modified: 07-07-2026, 08:07 AM by LucienLeFranc.)
Actually, Kardis' brain is in better working condition than mine . 
I now think it is correct that the speedo will be off.
What I failed to consider is that the 160 is meant to go on a wider rim, and so when you squeeze the tire onto the 140 rim, the tire will push the diameter outward.
Kardis had an issue posting pictures here, so he sent me info via email--Ill post it shortly.
Thanks Kardis for patiently setting me straight!
This information does make me question using a 160 on our bikes, however.
Since the 160 is squeezed onto the rim and therefore pushes the tire outward, increasing the diameter, won't that also round the profile of the tire? A 160 tire on a 160 rim will have a different (flatter) profile that contacts the road surface than a 160 tire on a 140 rim.
If this is right, then I may stick with 140 tires as long as they are available, since a 140 tire on a 140 rim will preserve the profile that the tire designers intended. A "deformed" profile due to being on the wrong width rim maybe has a similar effect to a deformed profile due to running too low or high of tire pressure? The contact patch might be longer and narrower on straights and would transition differently into corners? At least other than the designer intended.
At least I think that's correct? But my brain has failed me before (recently) so let me know if I'm off base on this.
I wonder if there's an online simulator that shows how much a tire is deformed where it contacts the road due to mismatching the rim to the tire by 20mm? Maybe it's not such a big deal.
Interested in hearing from you knowledgeable folks!
I now think it is correct that the speedo will be off.
What I failed to consider is that the 160 is meant to go on a wider rim, and so when you squeeze the tire onto the 140 rim, the tire will push the diameter outward.
Kardis had an issue posting pictures here, so he sent me info via email--Ill post it shortly.
Thanks Kardis for patiently setting me straight!
This information does make me question using a 160 on our bikes, however.
Since the 160 is squeezed onto the rim and therefore pushes the tire outward, increasing the diameter, won't that also round the profile of the tire? A 160 tire on a 160 rim will have a different (flatter) profile that contacts the road surface than a 160 tire on a 140 rim.
If this is right, then I may stick with 140 tires as long as they are available, since a 140 tire on a 140 rim will preserve the profile that the tire designers intended. A "deformed" profile due to being on the wrong width rim maybe has a similar effect to a deformed profile due to running too low or high of tire pressure? The contact patch might be longer and narrower on straights and would transition differently into corners? At least other than the designer intended.
At least I think that's correct? But my brain has failed me before (recently) so let me know if I'm off base on this.
I wonder if there's an online simulator that shows how much a tire is deformed where it contacts the road due to mismatching the rim to the tire by 20mm? Maybe it's not such a big deal.
Interested in hearing from you knowledgeable folks!
***
Motoloves of my life:
2014 CB1100 DX
2016 XR650L