FXR rear - too small?

[maggot]

So I parked my FXR up next to another the other day, just had a casual look over the other one, as you do. Then I noticed his rear tyre was a tad bigger than mine! I had always thought my rear was a little on the small side, and I guess I was right, cos I checked the sizes vs the manual and such and it doesn't seem to match up..
Manual recommends 100/90-17 and the tyre on mine is a 90/80-17.
Now my question is, what kind of affect will this have on the bike overall?
It's a pretty recent addition, last six months, from the previous owner, so it has good tread, but the size bugs me.

Also, my other question is, the manual recommends tubed tyres, but both of mine are tubeless.. does this pose any problem?

I've kinda realised my lack of knowledge regarding tyres so I figure I may as well ask and be educated!

Cheers!

[Gibbo89]

So I parked my FXR up next to another the other day, just had a casual look over the other one, as you do. Then I noticed his rear tyre was a tad bigger than mine! I had always thought my rear was a little on the small side, and I guess I was right, cos I checked the sizes vs the manual and such and it doesn't seem to match up..
Manual recommends 100/90-17 and the tyre on mine is a 90/80-17.
Now my question is, what kind of affect will this have on the bike overall?
It's a pretty recent addition, last six months, from the previous owner, so it has good tread, but the size bugs me.

Also, my other question is, the manual recommends tubed tyres, but both of mine are tubeless.. does this pose any problem?

I've kinda realised my lack of knowledge regarding tyres so I figure I may as well ask and be educated!

Cheers!

Why did you not whip the other fxr's wheel off for a quick 'swaparoo'?

As for the other questions, perhaps you can answer them yourself slightly? Does the bike perform well at the top speed? Does it wobble? Does the tyre tread go down fast with your current type of tyre?

A bucket racer may know a good deal about your fxr eh.

good luck

[Henk]

Different size rear may have some effect on handling but if you aren't finding it awful don't worry. I think you are commuting it so ultimate stick probably isn't an issue for you.
As for the tubeless / tube thing you are better off without tubes, in your application the advantages are.
1. If you pick up a nail the tyre won't go down in one hit
2. The tube won't wear from rubbing on the tyre and rim and leave you with something the resembles swiss cheese that leaks like a seive.

With buckets and tubes the rule of thumb seems to be to replace the tubes once a year and before the two hour, so you're ahead on cost and aggravation if nothing else.

[SMOKEU]

You should notice that with a thinner tyre on the bike it will be a bit easier and faster to turn. You will sacrifice a little bit of grip, but if the tyre is reasonably good quality then you shouldn't really have a problem with grip on an FXR unless you're doing something stupid.