170 rear tyre

[banditmack]

is it possible tofit a 170 rear tyre on a standard b4 rim and swingarm?

[interfuse]

No.

[banditmack]

will a 160 fit?

[Thief400]

No

[PitterB4]

Several people have run 160s.  See this thread from the old board.

[Thief400]

I tried one along time ago, the handling goes for a crap and the chain hit the side of the tire.

[Maniac]

the handling goes for a crap and the chain hit the side of the tire.

Two very good reasons not to go that route.

A lot of people want bigger tires because they look cooler, which is fine and all, but the wider the tire the worse the cornering will be. Motorcycles lean when they turn, but when you start getting a wider tire... well, take a car tire and a motorcycle tire. Stand them up like they would be on the vehicle, then let them go. The motorcycle tire tips, the car tire doesn't. Which one do you think will be easier to lean into the corner?

[banditmack]

why do all superbikes come with huge rear tyres?

[Maniac]

Traction!

I mean, really, at over 150hp would you expect a narrow tire to be able to handle it? Those wider one's have a hard enough time of it. But for us, with the 50 or so HP we have, it's not much of a problem.

Most 'superbikes' are designed for flat out speed and accelleration, not high speed cornering. My buddy has a Ninja 600R, it's a nice bike. Not really a superbike, I suppose, but still more 'superbike' than a bandit 400, eh? Anyway, he's got a much wider rear tire. His Ninja will smoke my 400 in the straights, but once we hit the twisties I passed him. Had to, he was slowing -way- down for corners! I don't know if he was being cautious, or if that was as tight as the Ninja would turn. He's got almost 2 years of street riding on me, and was really impressed with how quick the little 400 turned.

But in the straights? All I saw was a green blur, heard a scream of an engine, and smelled the exhaust as he shot past.

[PitterB4]

why do all superbikes come with huge rear tyres?

…to get a larger contact patch, which is possible with a big fat tire… IF you have a big fat rim to put it on.  Putting a fat tire on a skinny rim changes the intended profile of the tire changing the turn-in characteristics and possibly REDUCES the contact patch.  Do this – take a piece of paper and hold it long-ways.  Bring the edges 6 inches apart.  It’s still pretty flat.   Now, hold the edges 4 inches apart.  You’ve just turned a flat, fat tire into a tall skinny one.

[banditcilik]

I can only agree with the latest opinion. Wide tyres used by superbikes are not only for looks, they helps in cornering too. They have larger contact patch when cornering and this is needed to counter the bigger centrifugal force of heavier bike. You can still ride a superbike fitted with 250 bike in a straight line with no problem but you wouldn't want to try cornering with them. It will be a disaster. But yes, wide tyres are for wide rim. The form are designed to be linear with bike leaning movement. If forcefully fitted to slimmer rim then you will change their profile to a rounder profile. The tendency to lean is very high. It will overreact for cornering. The other way around happens when a small tyre fit to a wider rim. The profile will be flater and the bike will tend to stay upright make it difficult for you to lean the bike.  It feels like it's against your will.
I think the safest way to fit wider tyres is to also change the rim. To avoid chain scratching the tires you might want to use a spacer in the front sprocket. Too many hassle.