tires

I want to change my tires on my 78 kz 400. The tires that are on the bike are 300s-18 front and 350s-18 back. i would like to put a little bigger tire on but not sure what would work or fit. Has anyone changed to a bigger tire on this type of bike, and if so what size and type were they.

On your stock rims? Different rims? How wide is the rim you want to use?

Rims are stock 18" front and back. I just want to go a little fatter.

The stock tyres are already on the limit for the rims, which is a 1.60 front and 1.85 rear. So wider tyres will, all else being equal, reduce handling and increase tyre wear. Both because you will force the tyre out of its intended shape, making it narrower and more pointy, giving a narrower contact patch and also less support/stability for the tyre.

That said, you can fit a 90/90 or a 3.25 or a 3.50 front and a 3.75 or a 4.00 or a 100/90 or even a 110/90 rear tyre on your rims. Not every model made will fit when it comes to the larger sizes, but in general you can force them onto the rims and they will stay there. And I'm sure there is at least one person out there that even managed to mangle a 120/90 tyre onto the rear rim. But that really is risking things and asking for an accident to happen.

You can see the appropriate rim size vs tyre size hear www.avontyres.com/motorcycle/roadrider

Thanks a ton for the info. Looks like i'll stay with something as close to stock as i can.

That is the sensible choice!

Or fit wider rims if you want wider rubber. Putting on wider rims and tyres will make handling heavier and also more reactive to bumps while cornering, but unless you go wild it shouldn't be a big issue. However, the ideal tyre would have zero width - if it wasn't for the need of comfort, carrying ability and grip

I do agree that the narrow rear wheel in particular looks a bit silly under that wide fender - I used to have a 1979 Z400G Custom - but I couldn't fault the handling of the thing. I ran a 3.25 front and 3.50 rear on my bike and were fully satisfied with everything save the look from behind. The Germans have a great expression for these narrow tyres; Trennscheibe :lol: