Fatter arse end??

[Porpoise_of_doom]

Has anyone seen or heard of a wider rear wheel being put on a Vision? I understand you can only go so wide a tire before it'll scrub on the swingarm, so has anyone used a wider swingarm or modified a swingarm to take a wider tyre? There was a thread on this around 2004 so thought I might resurrect the question as I'm looking very seriously into it  ;)

[YellowJacket!]

I think the general concesus was that a wider tire would only hurt performance.  As with any custom job though, I guess the more time and money you have to pour into a custom job, you just CAN'T say it can't be done.  Just look at some of the custom jobs that have been done recently or ar going on now.

I guess what it all boils down to is that there is no substitute for rider skill.  The Vision handles quite well as it is and given its power and current capabilities, a wider tire would best be suited for use with increased power, a larger swingarm, beefier suspension.....
If you are wanting to put it on just for handling, then you may be stretching the limits of the bikes capabilities.  8)

David

[treedragon]

YellowJacket has it

Wider tires were originally brought in as part of the race scene in an effort to disspell heat and retain traction under race conditions. It was felt that the trade off required with changed steering geometry, compensation for the bike being pushed outward, was worth it.

As someone who has done hundreds of thousands of k's on fast, wide tired bikes, a lot of them Yamaha's, I got the shock of my life when I parked my butt on an XZ again and hooned it through some corners. You get used to the wide tired way of things and can forget what it used to be like.

With a few alterations to the geometry and suspension, on "skinny" tires, the XZ can be made to handle very well indeed and I for one wouldn't change for anything even tho from behind mine does look like a toothpick supporting.......... no we won't go there

[QBS]

What I've gathered from years of motorcycle magazine study is that the main purpose of big/wide rear rubber on sport bikes is to provide a larger contact patch for big horsepower to transfer through, especially when leaned over.

[VisionMeister]

I agree, too fat of a rear tire hurts performance. It slows the steering (without geometry adjustments) , is heavier and so hurts acceleration and shock action, and usually increases the gear ratio (depending on profile). I'd tried running 120'/90s on the rear but never liked the results and switched back to the standard 110/90.
My last rear Avon only lasted about 2500 miles (110/90) so I just tried a new 120/80 Avon. I can tell I have increased traction but the 80 profile feel about the same as a 110/90. The jury is out on wear longevity.
110/90 = 99mm tire height
120/80 = 96mm tire height

just my 2 cents

You can get the wheel modified for bigger tires but it is expensive and you need a donor rim that can be cut up.

[YellowJacket!]

I think its more like "Fad" tire.
  8)
David

[Porpoise_of_doom]

Cheers lads. My last bike had a couple extra cylinders and quite a few more killerwasps and hence a wider rear tyre. Whilst the geometry was similar, at least ergonomically, the trailing front of the XZ would have to give it a more nimble feel in corners under race conditions (hopefully I'll test this at the local track just once when they have another Classic Day). What I have come up with however is the XV750 SE (shaft drive/ monoshock) of the same era had a 130/90-16 rear. Not so keen on the 16 inch rim though. Would going from a 110 to a 130 rear have any negative affects? There's no way I would go nearly as wide as the modern sports bikes, though a mate seems to think a ZZR1 Ninja swingarm/ wheel would be an easy enough swap  :D

I just wish this rain would bugger off so I can get some more paint down, or at least get some sandblasting done !!!!!!

On the subject and on a sidenote, would it be un-advisable to sand blast alloy parts? I bought 40 kgs of superfine sand today..

[Rick G]

I'd leave it alone, The bigger the tyre the slower the handling.  The extra traction will help nothing.

[Tiger]

Would going from a 110 to a 130 rear have any negative affects?

:) It WILL scrape on the upper arch of the swing arm... :o Also, the tire wall is pulled in at the rim and the centre of the tire is 'peaked', therebye giving less of a contact patch. Changing tire pressures to compensate does not work!!
         
I have one mounted on a rear wheel if you want to buy it :P

... so I just tried a new 120/80 Avon. I can tell I have increased traction but the 80 profile feel about the same as a 110/90.

This is what I have ran on "The Mistress" for the last 2 1/2 years and it works very well... 8)

     8).......TIGER....... 8)

[Porpoise_of_doom]

Sweet. Actually kinda glad you talked me out of it gents, you've no doubt save me a bit of cash!

[jasonm.]

The 'bigger is better" idea does not always work. Especially with tires. I think the Seca Turbo had a wider rim on the back that looked just like the Vision. But 120 is as far as I would care to go on the original rim.