This is always such a huge debate in here and actually every single bike forum I have gone in. Let me just say 1 thing(I'm sure someone will argue with me), Honda didn't exactly spend that much time engineering this bike. Manufacturers are more concerned with price when it comes to their lower end vehicles, and most of the time they barely break even. They do this so that you enter their brand and hopefully are pleased and will move up models with your next purchase. Honda's bikes like the 600rr and 1000rr I am sure put A LOT of engineering time into balancing, road testing, wind tunnels etc etc. So I never go for the excuse 'if they thought (X) would make the bike better or faster they would have built it that way'. Not true. I know a Purchaser for Ford that specifically looks to find materials that save a penny on the dollar, that's part of his job to do, even if it means a different supplier from model year to next model year.To each his own ...but I think that since Honda engineered this bike and it came stock with 140/70/17's on the rear myself I plan to stick to stock sizes. Do you guys realize that in Motto GP the 250's are fitted with narrower tires (with alot more power) than our 300's have. This is by design to help with the bikes handling. Like I said ..to each his own.
You're right. Big tires create additional counter forces pushing the bike up in corners. The largest bike I ever rode had a 240 rear tire. It's difficult to compare that with a CBR300, because the wheel base and weight is also much different (1380mm / 164kg to 1695mm / 370kg). So the CBR corners much easier than the cruiser ;-)From what I have read...a bigger rear tire would interfere with how the bike handles in a flick-able way.
Late to this party but perhaps good for others with the same idea:I know many people discourage to change the tire to 160, but I want to do it for the aesthetic purpose. What kinds of mod do i need to do to make it happen? I saw this mod done in Thai and i looks gorgeous. I believe the tire is large than stock. Also, if anyone can help, what mods did this owner did to this bike? I just ordered my bike, and its coming next week, i can't wait. I'm also a first time rider and CBR300R will be my first bike. Thank you in advance cheers