Does anyone know the biggest tire size that i can put on this bike FRONT & REAR?

Is it Recommended?(More traction)?

 

Lower pressure will give you more traction not fatter tyres. 120 on the rear is good but you'll be pushing it fitting a 130 or 140. Most 21" fronts are pretty much the same.

 

The heavier the tire, the more engine power is used to rotate that tire (which would mean less power available to be used for forward motion of the bike) Correct me if I'm wrong, but that is the impression that I've gotten.

 

True but once up to speed the flywheel effect of a heavier tyre can be a positive especially when climbing long hills.

 

Good point!

 

Flywheel effect in effect. ;D

http://www.youtube.com/watch?v=zqNYtI-0O2s

 

I'm having faded flashbacks from a long gone physics course!

http://en.wikipedia.org/wiki/Moment_of_inertia

Uhhhhhhhhhhhhh. oh yeah!

 

as far as 18 inch dirt tires go, you can fit a 130 but thats going to be it. ive done it, and would advise against it. the bike feels like a tw200 when you lean then, and provides no more traction than a 120, or even a 110. from all the tire sizes i have tried, ive found tire size has nothing to do with traction, but more the tread pattern and tire compound deals with that. whats your reason for going with bigger tires, there might be other ways to find what your looking for.

 

I have a D606 130 on mine now. I haven't noticed any negative effect, but also no real positives either. (one negative is that the 130's cost more) I will go back to a 120 after this one wears out.

130 on the left and a 120 on the right , both dunlop d606's

 

I was hoping for better traction, since i wiggle alot on the freeway and i figured wider tire = more grip.