Largest tire size.

I am looking for the largest but safe tire size for my 1976KZ900.I am going with the Avon Roadriders.
I have some old and cracked sizes on.
front,100/90/19
rear, 120/90/18.
I think stock is 3.50/19 and 4.00/18.

I am not familiar with the metric sizes but i got a tape out and they look ok if i am reading it right!
It looks like there may be a little more clearence in the rear but the front looks to be close right now with the sizes on there.
Any help would be great.Thanks,Rex.

The stock tires on that bike are 3.35 front and a 4.0 rear. in the Avon AM26 that you want to use that would equate to the AM26(Universal)100/90-19 front and the AM26(universal) 110/90-18 rear. But the roadrider is available in the original size of AM26(universal) 3.25-19 front and AM26 4.0-18(rear) rear. So just get the OE size and you will not have a problem with the spedo being off.

By the way, those are excellent tires.

Thanks for the info.Your right.I will stick with the OE
size.The KZ clymer manual i have states the front stock size to be 3.50/19 ? It is a clymer though.What do you think?

The Clymer is wrong. It is a 3.25 front. If you want to go with a 120 rear that would be no problem. You might even be able to fit a 130 without hitting the chain.

That sounds about right.I thought it might be wrong.
I will go with the 3.25 front and 120/90/18 rear.
Really appriciate experienced info.

otakar wrote:

The Clymer is wrong. It is a 3.25 front. If you want to go with a 120 rear that would be no problem. You might even be able to fit a 130 without hitting the chain.

I fit a 130 to mine, but I'll be going back to a 120 after these. I think it adversely affected handling, I get a lot of slip when doing in-town slow speed intersections and punching it - more than I used to with a 120 (could just be the tires model as well).

When you start putting wider tires on narrower rims, you wind up with excessive side wall flex. This will cause the tire to shift side to side as you start putting pressure on it in hi speed turns. That is definitely not what you want.

Bingo! I ran 130's on the back of mine for years, but they don't work better (or maybe not as well) as 120's. The 130 tire ends up distorted because it's pinched on the narrow rim so there's actually no more contact patch than a 120. Plus they're a royal pain in the butt to mount. I won't be going back to a 130. Ed