120/70 Front tire

Bill Wu

New Member
Has anyone tried 120/70 front tire on RC 390?

Will it touch anything like fender or anything else?

Hope someone can share the experience. Thanks!
 

big_sur

New Member
No, it fits fine, though warmers will be tight. It doesn't have the feel or agility of a 110, but it might be better for rough roads.
 

Bill Wu

New Member
No, it fits fine, though warmers will be tight. It doesn't have the feel or agility of a 110, but it might be better for rough roads.
OK, thanks a lot for sharing. I just want to try add some contact patch at the front.I use Heidenau K80 tire, the 110/70 front tire has no extra contact patch, but the 150/60 rear tire still has some contact patch.Thus, I'd like to try the 120/70 front.
 

ToraTora

Member
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Bike tires are not like car tires where when you change sizes you basically get just a different diameter of the tire. With bikes you end up with a different profile, and that can cause issues.

The problem with going with the wrong size tire is that you go from the intended more V shape to the unintended U shape. What happens is when you lean you get less rubber on the road in a corner than you would with the proper tire profile. It's also harder to get the bike to go into the lean. Another issue is that when in the lean the bike will be inherently less stable because you have a sharper edge radius.

So in general it's much better to get a tire designed for the wheel you have than to use a tire designed for a different sized wheel.

tire shapes.jpg
 
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