Sorry, I tried the search function but can't easily find the answers.

Am I right that the stock tyres are 110 on the front and 120 for the back?

And how wide on the back can I go before the tyre bows and changes shape? I want wide but I don't want to sacrifice too much safety by changing the way they are meant to hit the ground while dragging knees.. I won't actually knee drag as I'd like the Midas E08 dual sports but I'd still like to throw myself around corners as much as, or as close to as much as the tyres are designed.

I'm thinking 120s for the front and 140s for the back..

Stock is 110 front and 130 rear.

120 front and 140 rear works fine if you can't get the stock size in the tire you want.

that size will work, just be aware that depending on the tire, it may wind up being quite a bit more tippy/twitchy than it is with stock size tires. The Shinko 705s in 120 & 150 on my GS were borderline scary when I first mounted them and are really only stable when the pressure is in a certain (very high) window.

Great, thanks for both your replies. So my 120 and 140 plan should pass and be closer to the stock if pumped up hard. Thanks, I might even find a way to trace the stock tyre shape and see the difference with the swap.

Just saying if it feels tippy, try higher pressure. I wound up with 38F 41R on mine. You may not have any issues.