hey everyone i need some help with tires, im goin to buy tires tomarrow, and i am wondering what is the difference between a 120-60-17 and a 120-70-17, i currently have a 120-60-17, and my buddy has a 120-70-17, can anybody please tell me what the difference is between these two sizes....120-60-17 and 120-70-17.....thanks

 

The 120/70/17 is a taller tire...it will still work though..
RB

 

When I purchased my bike a couple months ago it was wearing old metzlers. The front was a 120/50/17 and wassquared off and chicken stripped ( I GUESS that's the proper term, maybe cupped is better) and the rear was a on a 5" F3 rim it was a 180/70/17. I went back to stock sizes (with an F2 rim) in Avon Storm STs and WOW!!! those are great tires. They may not grip like the dedicated sport tires but they are fantastic on wet roads. Comparing them to 5 year old Metzlers that had sat outside for four winters and five summers would be unfair, butmy suggestion to anybody using these machines on the street is to stay with the stock size and buy the best tire your wallet will tolerate.

 

A 120/70 is a taller tire,but it also has a larger contact patch when leaned over.Always use this size on an F2 or F3.

160 or 170 rear tire is best for these bikes also.A 180 will slow the handling down and upset the front if you're going "full tilt boogie" in the corners.

Can't go wrong with Michelin Pilot Powers or Metzeler M3s for sport riding.Cycle Gear is cheapest out this way.

Taz,you wanna sell that F3 rear wheel?

 

There is a significant overall (outside) diameter between the two. The technical answer is this and will also show you what the difference is:

The middle number (in this case 60 or 70) is an aspect ratio of the height of the sidewall (on any give section measured 90 degrees from the wheel)in relation to the width of the tire (in this case 120mm). So, a 120/60 = sidewall height of 120mm*.6 = 72mm

We would then take that number and multiply by 2 since there are "two" sidewall height measurements (one on "top" of the wheel and then below that 17" space there's sidewall on the "bottom" of the wheel) = 144mm

Convert that to inches = 144/25.4 = 5.67" AND then add the 17" wheel diameter in between it all for an overall outside diameter (OD) of 22.67" for the 120/60/17

The 120/70/17 = 120(.7)(2)/25.4+17 = 23.61" OD

So there's almost an INCH in overalldiameter difference. HUUUUUGE when you figurehow muchR&D the engineers of that bike put into it to figure how well everything (from suspension, handling, rider feedback, etc.)will work with a specific size tire.

DO NOT DEVIATEfrom the OE size.

Good luck andride safe.