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I had my rear rim converted to take a 180 section tyre about 15 years ago by Georg Deget, who is the fella that does them for the German Z1300 shop. They're German TuV approved so no concerns about safety. The diameter was also increased from 17" to 18" as modern rubber has a lower profile which would have the effect of lowering the overall gearing. The wheel is offset by 20mm (about 7/8 of an inch), which I was initially dubious about but I've not noticed any issues with handling. Some bikes came from the factory with offset rear rims -one example is Moto Guzzi who did it back in the 80s so that they could fit wider rubber inside the confines of the swingarm. I don't have a standard swingarm (it's a JMC underbraced alloy unit) & it did need to have a portion machined out on the drive shaft side, I know that the standard swingarm needs metal cut from the same area & then a gusset welded in to maintain structural integrity. Not sure you'd have to do the same with a 160 though as from memory going to a 170 only entailed grinding the prominent seam flush on the inside of the swingarm for clearance then re-welding it. Getting the 180 rear wheel in & out is a faff, it's a real juggling act, as the shaft bevel box has to come off & then maneuvered in or out of place at the same time as the wheel lol.

Without using the 'quote' marks, that's exactly it Phil. Looking at my swing arm, a future chosen by me 170 would require that protruding welded ridge removed - it can be just an inch, then welded for strength.

It's correct - some bikes come with factory offset, about which even dealership mechanics don't know. That was the case with local Yamaha shop. With bigger offsets there could be a feeling of easier leaning turning one way than the other, but otherwise no adverse handling effects. Well, having 5 inches offset would obviously not be advised LOL

Good to hear that in case of 1300's a 180 tire doesn't require notching. I will be staying with that Continental 170 I chose though, as from the tire size calculator it seems like it keeps the same side wall height as original tires, and I am keeping the original wheel. Of course there would be some particular minute differences between brands.

Hi Kenny
I've notched my KZ's swingarm by cutting & adding material.I now run a 180 Pirelli Angel GT.
No offsetting was necessary and I have a clearance of about 2 mm.

Very nice! I'm going conservative
widening Just going up to 165 mm. The company that may do the widening says that they can make it a 18". So I may do that as well.

If I do go bigger meaning from 17" to 18" can I still use the standard shock size?

Kenny
I'm sure if you go 18 the travel on the shocks will be enough ?
I bought nitro assisted shocks from Australia and they work pretty well.

Divman wrote: Hi Kenny
I've notched my KZ's swingarm by cutting & adding material.I now run a 180 Pirelli Angel GT.
No offsetting was necessary and I have a clearance of about 2 mm.

Are you running the 180 on a stock wheel?