The main difference is that the size 120/65/17 is the perfect medium between tires... the point of getting bigger or smaller tires is the main feeling of turning... say youo trade the stock 120/65/17 for a 120/70/17, the bike will pull out of a turn better, but it won't turn into the turn as well... same as if i were to trade down from a 120/65/17 to a 120/55/17, i would be able to enter a turn better, but i wouldn't be able to exit it as well as i could with a stock size of 120/65/17... but then again if your not a real hard twisty rider and mainly use the bike for commuting, you won't feel a big difference, heck you may not even notice any difference at all... but changing tire sizes in the middle of a track day, you'll DEFINATELY feel som change... so yea, stock 120/65/17 is a perfect tire size, but if you don't really care to much about turning, and don't turn to hard, just settle for the 120/70/17...
I think I am more confused after reading that than I was before hand...lol
The 65 series is the middle of the road like was said. you can get the 120 in a 60,65,and 70 series sidewall.
The 70 series is a little taller than the 65, will slow the turn in down just a little and tends to make the bike more stable. you can run the 70 with no problems, maybe if absolutely needed drop the forks 5mm if need be.
try using the search function next time, there are at least 30 threads of the same question with alot of info that will help you out.
$0.02 here… from a FEEL PERSPECTIVE I feel less stable in the twisties w/ a 60 on the bike. Almost like the front end is going to wash out. 65 feels pretty good and allows more dive into the corners while feeling a lot more stable than the 60 (for me). Perhaps because of the perceived stability in the bike; it feels more stable and solid. Going to a 70 will slow the dive into the corners a little but may not be very noticeable especially if you are hard on the front end while diving into turns. The 70 also feels like it adsorbs more bumps, etc because of the taller side wall; this applies to both straight line riding and in turns. From 60 to 70 as the number gets higher you have more potential rubber on the road at lean. All in all if you feel comfortable and confident in the front end feel of your bike, the faster and safer I think you will ride. More concentration can be applied to the ride and what is coming up next versus being scared that the bike will wash out at any time. That might make you want to park the bike after a few of those moments… I personally experienced the 70 series tire raising the bike in the front (I did not adjust suspension from a 65 to 70 on my 06 6rr) and it didn’t feel as solid as the 65 series. If you are a straight line rider and don’t favor canyon carving then you may not even notice much the behavior differences from 60 to 70 other than the ride being more stiff w/ the lower profile. Around town driving might be easier w/ a 60 cause it truly turns a bit easier. Getting too long here… hope it wasn’t confusing. -will
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