kz400 tire sizes

The stock kz400 calls for a 3.25/18 front yokohama and a 3.50/18 rear yokohama. On every conversion chart i have seen a 3.25-3.50 /18 is equivalent to a 100/90/18 tire. The kz400 comes with 1.85 rims front and back. The 90/90/18 from Avon has a minimum recommended rim size of 1.85. The smallest rim size for100/90/18 tire is 2.15. I was planning on running the avon 90/90/18 front and 100/90/18 rear but this would be too small rim suggested by avon for the rim. It seems the kawi was going to big from the factory. should i go 90/90/18 on the rear too?

side note. is it possible the rim measuring system then has changed just like the tire measuring? So the 1.85 is more like a 2.50

btw the bike currently has a 3.50/18 front and a 3.75/18 rear from the PO

You can go 100 on the back no problem. I've seen guys go 110 on a 1.85 rear before, although it's not ideal.

It's hard enough to get my paws in the tire/rim to put in the valve stem. Any smaller, I couldn't do it. Try Chaparral to see what they have to offer. I have a 110/90 on the front and there is no room left. The 100/90 would wash out too easy on dirt and squirrely on the turns. I have a 130/90 V rear. I'd like bigger but not in the program.
Steve

thanks for moving this admins.

I have 3 78 kz400's with the spoke wheels, I am running 110/90/18 on the rear and 100/90/18 on the front on two of my bikes. On the third one that I chopped, I'm running a 110/90/18 on the front and it barely clears the fender mounting bolts and I don't ride that one nearly as hard either, but it does fit. All my bikes have 1.85 fronts and 2.15 rears, however I have a kz400 part-out that I saw has a 2.15 front, not sure if that was someone relacing that wider rim to the front hub or if it was somehow like that from factory (maybe the deluxe model?). I also had a kz440 partout that I think had 1.85 front and rear and came with 3.00-18 tires on it which looked riduculously skinny.

90/90/18 & 110/90/18 on my KZ400 that has the stock rim sizes.
The other bike with a 2.15 rear is 100/90/18 & 120/90/18.

The deluxe is like the other 400's with a 1.85 rim front and back. I went with a 90/90/18 front and a 100/90/18 rear Avon roadriders. thanks for replies guys.

I have a 79 kz400 ltd and I. The fro t it has 100/90/19 and on the rear it has 130/90/16 is this correct.

Which year KZ400 had 2.15 spoked rear wheels? I've been reading here trying to find the answer, but all I came up with is that some have 2.15 wheels and some 1.85.
​​​​
I would like to swap the 1.85 I currently have for something wider, so far the easiest way seems to be a 2.15 from another kz400.

Maybe lace a 2.5 wheel on to the hub?

What is your experience with this mod?

Which year KZ400 had 2.15 spoked rear wheels? 

Possibly the Ltd models.  the 79 400H Ltd had cast alloy wheels.
Kawasaki.com and Partzilla have parts diagrams but partzilla is easier to use, since you can zip around from model to model a lot faster.

Thank you Martin_csr for taking the time to reply.

I tried Partzilla, they list the part numbers but do not have the wheel size listed with it.
I see 3 different part numbers but no way to tell which one is 2.15.