Originally Posted by dennisgb

It basically is about the amount of force applied to the frame and suspension due to adding more tire contact surface or due to softer rubber compounds which grip more. While it seems like more tire would be better, that assumes that the bike is designed to take the increased forces. I know with my Norton this is a big issue because the frame has a tendency to flex even with the standard tire sizes.


This is much more complicated than most of us understand. The original F1 design was based on the available tires and was tested extensively during the design phase to insure that the component designs were sound. If you read about the development history Honda was very conservative and took 2 years to develop the Hurricane even with strong competition from other manufacturers. They were pushing the limits of the technology.


The biggest issue we owners face now is the very limited selection of tires because of the evolution of the bikes. Rubber compounds have improved considerably and that alone results in extra stress on the frame and suspension even when using OEM sizing. Adding additional width and subsequent tire contact area just increases the stress to the bike.


It would be interesting to do a study on F1's with frame cracks (a common failure) and see what tires were on the bikes during their lifetime. It could be related.


The main point that I am trying to make is that increasing tire width in order to get a more modern look is not a good idea without looking at frame, swing arm, wheel and suspension modifications in order to insure the integrity of the bike, not to mention the profile issues with putting wider tires on the wrong wheel width.


In my opinion the 110 front tire is the best choice with the existing front forks and suspension. A wider tire up front will change the handling and slow down response. Fork tube flex may also come in to play due to the increased contact area imparting higher forces particularly during braking. There really isn't much structure holding the fork tubes from rotating or twisting not to mention bending in severe cases. The yokes also will have increased stress and given that original the design and development was controlled by minimizing weight it would be interesting to know what safety factor was used in the design of these components.


I think that anything wider than 140 on the rear using the stock wheel will change the profile enough to create handling problems and stress the tires in a way they were not designed for. The additional contact surface even with a 140 tire along with the softer rubber compounds in most newer tires could impart additional stress to the frame and suspension so that should be considered and I would keep an eye on the frame in the areas known to crack.


I realize there are a lot of owners who have wider tires on their bikes and believe they handle fine. I'm not saying you can't do it, just be aware that you may be pushing the limits and there could be issues.

Originally Posted by Emmanuel Lind Chrisalos

So with your insight on the issue you men that i made a big mistake buying Pilot Street Radial Front 110/70 and Pilot Street Radial Rear 140/70 R17. I am not picking a fight, only asking your opinion sins i care more about the functionality of the bike than the looks. Like i have mentioned earlier i like to ride hard.

Originally Posted by dennisgb

No, those tires are probably fine. The point I made about frame cracking is just conjecture on my part, and something everyone should keep an eye on regardless of tires.


https://cbrforum.com/forum/cbr-600f-...k-frame-57248/

Originally Posted by Emmanuel Lind Chrisalos

Yes my bike had it when i got it and the first thing i did was to fix it. Cant have a bike split in 2 under hard cornering can we now