KZ1000A1 Rear Tire Size in Metric

I'm having trouble sourcing a replacement for my 4.00 x 18 Avon Roadrider AM26 rear tire. I should have bought one to have on hand earlier this year when I replaced my front, but didn't. I know they are switching production to the Roadrider MKII, but the 4.00 x 18 is OS everywhere I can find in Canada. Of course, going across the line to the US is out of the question right now since the border is closed and will remain so until this Covid thing is under control. I've read that a metric substitute would be either a 110/90 x 18 or a 120/80 x 18. I've found a MKII 120/80 x 18. Will it fit?

The 110/90 x 18 will be very narrow. I cannot say how well the 120/80 x 18 would work. The best size is 120/90x18. I've been using that size for many years. I have even used a 130/90x18, but the narrow rim somewhat distorted the tread shape, so the 120/90x18 works better. Ed

Pirelli makes their rear Sport Demon in 120/90-18.
Also their MT 66 Route.

www.pirelli.com/tires/en-us/motorcycle/a.../catalog/on-road/all

650ed wrote: The 110/90 x 18 will be very narrow. I cannot say how well the 120/80 x 18 would work. The best size is 120/90x18. I've been using that size for many years. I have even used a 130/90x18, but the narrow rim somewhat distorted the tread shape, so the 120/90x18 works better. Ed

Thanks Ed. My current 4.00 x 18 Roadrider tire measures 4.6" wide, or 117 mm, so the 120 looks like the closest width, if indeed it's 120mm wide. The MKII comes in both a 90% and 80% aspect ratio, so I'll order the 90 if it's available.

BCScott wrote:

650ed wrote: The 110/90 x 18 will be very narrow. I cannot say how well the 120/80 x 18 would work. The best size is 120/90x18. I've been using that size for many years. I have even used a 130/90x18, but the narrow rim somewhat distorted the tread shape, so the 120/90x18 works better. Ed

Thanks Ed. My current 4.00 x 18 Roadrider tire measures 4.6" wide, or 117 mm, so the 120 looks like the closest width, if indeed it's 120mm wide. The MKII comes in both a 90% and 80% aspect ratio, so I'll order the 90 if it's available.

A 120 width tire will measure wider than your 4.00 tire does now once installed. Kawasaki used a lot of 120's on bikes that use a 2.15" wide rim, although many people would say that tire is too wide for the rim. Regardless, it will work so I'd go ahead.