SSA Sierra Sportbike Association | Reno Nevada Motorcycle Trackday Weekend Riding Club

General Chat - Weekly Rides, Bike Discussion, & More . . . => The Garage => Topic started by: BovineFreedom on August 28, 2010, 11:17:09 PM

Title: Tire size question
Post by: BovineFreedom on August 28, 2010, 11:17:09 PM
Hey guys, I am in need of a new front tire. My buddy has one with 80%+ tread left but its a 120x60x17 and my bike has a 120x70x17. Will that 10mm difference in height cause any problems with handling? Low on funds and can't really afford a new tire at the moment. Thanks
Title: Re: Tire size question
Post by: jlavallee on August 29, 2010, 07:41:34 AM
Quote from: BovineFreedom on August 28, 2010, 11:17:09 PM
Hey guys, I am in need of a new front tire. My buddy has one with 80%+ tread left but its a 120x60x17 and my bike has a 120x70x17. Will that 10mm difference in height cause any problems with handling? Low on funds and can't really afford a new tire at the moment. Thanks

The 70 is an aspect ratio not a direct measurement so it'll be a little more than 10mm. the bike will steer a little quicker and generally have a little less contact patch at lean since (assuming they're the same brand/model) the profile will be a little flatter. Essentially, it is nothing that you will really notice for normal street riding. Go for it.
Title: Re: Tire size question
Post by: TWF on August 29, 2010, 03:46:15 PM
Quote from: jlavallee on August 29, 2010, 07:41:34 AM

The 70 is an aspect ratio not a direct measurement so it'll be a little more than 10mm.
Maybe, maybe not. stamps on tire mean nothing. To know exact difference you need to measure it. I have 60 series tire that is bigger than 70.
Title: Re: Tire size question
Post by: jlavallee on August 29, 2010, 05:28:15 PM
Quote from: TWF on August 29, 2010, 03:46:15 PM
Maybe, maybe not. stamps on tire mean nothing. To know exact difference you need to measure it. I have 60 series tire that is bigger than 70.

True, hence my note that it is assuming they're the same brand/model.
Title: Re: Tire size question
Post by: BovineFreedom on August 29, 2010, 05:46:35 PM
Thanks for the info guys.  Now to get it installed.
Title: Re: Tire size question
Post by: Scott on August 30, 2010, 12:19:14 PM
here's a good explanation and breakdown of motorcycle tire sizing.
http://www.retrocycle.com/tiresizes.php (http://www.retrocycle.com/tiresizes.php)
Title: Re: Tire size question
Post by: A DRAGON on September 04, 2010, 06:09:26 AM
Quote from: BovineFreedom on August 28, 2010, 11:17:09 PM
Hey guys, I am in need of a new front tire. My buddy has one with 80%+ tread left but its a 120x60x17 and my bike has a 120x70x17. Will that 10mm difference in height cause any problems with handling? Low on funds and can't really afford a new tire at the moment. Thanks

Bovine.  I understand your concerns.  I would just mount it.  If your on  a race track turning mad skills time. It's something you should worry about.   I used to.  Now for the street I just mount it. 

Races are flipping tires on the race track now.  It's unbelievable what people are doing now.  A rear is a directional tyre.  It's now turning the opposite way and it still works.   Fronts I'll even mix and match the brands.  I haven't had a problem..  Sometimes the new height rubs my front fender.  Haven't broken it yet.   

Do what ever you feel comfortable...  What I do works for me.  Good luck :2cents