110/80-19 120/80-18 tires on a KZ550 with stock rims

what I've been planning to purchase is a front 100/90-19 and a rear 120/90-18.
However, because my KZ550 is a "Tracker/Scrambler" style build and I'll be doing some trail and off road riding, the tires need more bite.
Based on the 20%/80% (off road/street) tires I've seen, I have not found a set that matches my size criteria.
I have however found the tread I like in 110/80-19(front) and 120/80-18(rear).
How might this, change in size, effect handling and wear on a KZ550A with stock mag rims?
I'm guessing that there would be less side wall height and a more arched tread surface?
in terms of clearance I have only the swing arm and the front forks to worry about. Fenders, chain guard, etc are not an issue/can be modified.

IIRC the KZ550 has a 1.85x19 front wheel. Not sure what tires you're looking at but most manufacturers will have a range listed for appropriate wheel sizes. with the most ideal being in the middle obviously. Just out of curiosity I looked up 110/80/19. The recommended rim size is 2.15-3.00 on Avon's site. When you put too big of tire on too small of wheel the profile gets distorted and because of the excess material on the rim the tire becomes much more "floppy" on the rim. This translates into worse handling, braking, and premature tire wear. You might get a tiny bit more traction from 20/80 tire, but the sloppiness that an oversized tire will impart will probably negate the little traction you gain.

IMHO 20/80 dual sport tires are mostly just for looks. They hobble a street bike, and if that bike does see unpaved roads its typically not worth the negligible traction increase. I have rallied sport bikes on dirt roads quite a bit and I personally don't see the need for 20/80 tires. Once you get a little more serious like a 40/60 or 50/50 then there are advantages.

DoctoRot wrote: IIRC the KZ550 has a 1.85x19 front wheel. Not sure what tires you're looking at but most manufacturers will have a range listed for appropriate wheel sizes. with the most ideal being in the middle obviously. Just out of curiosity I looked up 110/80/19. The recommended rim size is 2.15-3.00 on Avon's site. When you put too big of tire on too small of wheel the profile gets distorted and because of the excess material on the rim the tire becomes much more "floppy" on the rim. This translates into worse handling, braking, and premature tire wear. You might get a tiny bit more traction from 20/80 tire, but the sloppiness that an oversized tire will impart will probably negate the little traction you gain.

IMHO 20/80 dual sport tires are mostly just for looks. They hobble a street bike, and if that bike does see unpaved roads its typically not worth the negligible traction increase. I have rallied sport bikes on dirt roads quite a bit and I personally don't see the need for 20/80 tires. Once you get a little more serious like a 40/60 or 50/50 then there are advantages.

thanks, i think that’s the nudge i needed to stick with road tires. i don’t like the idea of loosing performance on street.
i’ll just try to pick out street tread with the biggest grooves. driving across a damp field might be tricky