What size tyre to choose

[Kenny]

Hi all.
i need a new front tyre. In the front there is a old tyre with size 3.25-19. In the rear it is 110/80-18. What would be better to choose: 90/90-19 or 100/90-19. And if one is better than the other please tell me why so i can learn a bit as well.

the bike in question is a 1978 gs500e 4cyl.

[Steve]

Either one will probably fit and work well enough. The 90/90 is closer to the stock size and is nearly perfect. The 100/90 is approaching the limits of what can be safely supported by a rather narrow rim, but it is slightly larger diameter, which is just about enough to eliminate the usual speedometer error.

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[Nessism]

You can run 100/90-19 front and 120/90-18 rear if you want. That's the widest I'd go though. I ran those sizes on my 550 and the bike handled nicely. Kawasaki KZ bikes of the GS era used the same size wheels along with those size tires from the factory so don't let people tell you the sizes are too wide.

[Kenny]

Ok, thanx guys!!😀 Appreciated.